HSX38186
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HSX14410.1177/1088767910381864Reasons et al.Homicide Studies
© 2010 SAGE Publications
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The Ideology of
Homicide Detectives:
A Cross-National Study
Homicide Studies
14(4) 436–452
© 2010 SAGE Publications
Reprints and permission: http://www.
sagepub.com/journalsPermissions.nav
DOI: 10.1177/1088767910381864
http://hsx.sagepub.com
Charles E. Reasons1, Teresa Francis1,
and David Kim2
Abstract
Ideologies help guide our behavior and thought processes and have been largely
neglected when studying crime and criminal justice professionals. Intensive interviews
were conducted with homicide detectives in Seattle, Washington and Vancouver,
British Columbia to provide a view of their working beliefs and opinions concerning a
number of issues. The areas questioned included (a) working environment, (b) causes
of homicide, (c) television portrayal of homicide work, and (d) the death penalty.
Within each area several questions were asked. Although homicide detectives in
both cities and countries gave similar responses to many questions, they differed
significantly in terms of the role of guns, particularly handguns, in homicide rates, the
death penalty, and their relationship to the prosecutor/crown. Therefore, although
their constellation of beliefs (ideologies) surrounding the above noted topics were
in many ways similar, there were distinct differences. The areas of difference can be
understood within the larger legal and cultural context.
Keywords
comparative homicide, ideology, homicide detectives, causes of homicide, police work
An ideology is an organized collection of ideas. All societies have an ideology that is
the basis of “common sense” or “public opinion.” It often appears neutral. A “natural”
given set of assumptions not often challenged. For example, the notions that the United
1
Central Washington University, Ellensburg
Washington State University, Pullman
2
Corresponding Author:
Charles E. Reasons, Department of Law and Justice, Central Washington University, Ellensburg, WA
98926-7580 reasonsc@cwu.edu
Reasons et al.
437
States is the best country in the world; democracy as we practice it is the best form of
government; government control of the economy is bad; what ever is good for the private sector is good for all. Although we are all socialized with an ideology, those who
conduct the study of crime often eschew the term ideology and ignore its role in the
study of crime. The criminologist is often viewed as insulated from ideology because of
his or her methodological strictures.
In his classic work Ideology and Crime, Sir Leon Radzinowicz (1966) details
how explanations of crime have changed with changes in society over many centuries. Although most criminology and criminal justice texts outline the changes in
ways of explaining crime from demological to classical neoclassical, positivist
and critical explanations, the role of ideology is largely ignored. Explanations of
crime are presented as a linear, cumulative progression in our understanding of
crime. If one looks at current textbooks, rarely is there a notation for ideology in the
index. This omission is due in part to the largely “normal science” of criminology
and its emersion in positivism and scientism. A cursory review of major criminology and criminal justice journals provides evidence for this dominance of scientism
and positivism.
In the “Professional Ideology of Social Pathologists,” sociologist C.W. Mills
(1943) observed that social scientists and academics share collective ideas and
“ways of thinking” (ideologies) in the study of crime and deviance related to their
backgrounds and biases. More recently Kelleher (2001) provides an update to Mills’
argument by arguing that contemporary students of social problems have a liberal
bias in their work. In the “Sociology of Nuts, Sluts, and Perverts,” Liazos (1972)
discusses this in terms of the focus of criminological study. In the Social Reality of
Crime, Quinney (1970) provided a break with the positivist tradition in emphasizing
how both law and crime are socially created and pursued based on factors of race,
class, and other biases.
Although we all have ideologies, lay people and social scientists, most research by
criminologists on ideologies and beliefs has been on the offenders and/or employees of
the criminal justice system. In a significant, but now largely ignored, article “Ideology
and Criminal Justice Policy,” Walter B. Miller (1973) provides an excellent starting
point for addressing the role ideology plays in the criminal justice system. He identifies ideological positions on the left and right and summarizes crusading issues and
general assumptions. These are presented generally, and then he discusses four professional groups. (a) Academic Criminologists (b) Judiciary and Courts (c) the Police,
and (d) Corrections in terms of the left/right positions. He concludes,
If, as it is here contended, many of those involved in the tasks of planning and
executing the major policies and procedures of our criminal justice system are
subject to the influence of pervasive ideological assumptions which are largely
implicit and unexamined, the question than arises What are the consequences of
this phenomenon? (Miller, 1973, p. 150)
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Homicide Studies 14(4)
Police Ideology
In discussing the ideology of the police, Miller (1973) notes that most have “working
class backgrounds” and most fit into the “right” classification ideologically although
there are variations in region of the country, size of department, age, and rank differences. This is largely confirmed in the classic research on the “working personality”
of the police decades ago. However, Walker and Katz observe in their more recent text
Police in America (2008), the attitudes and culture of police are more complex today
given the dramatic changes in the rank and file over recent decades (Women, African
Americans, Hispanics, gay and lesbian officers, higher education level). Nonetheless,
there are “ways of thinking” among police today.
Little research has been conducted on detectives, generally, and less on homicide
detectives. Walker and Katz (2008) point out that detective work is surrounded by
myths largely because of movies and television police shows. Some of these myths are
that detective work is exciting, glamorous, and dangerous; detectives possess exceptional courage and skills and solve all crime. Although these myths are empirically
unsubstantiated, they produce harmful consequences, such as unrealistic expectations
from victims and the public, and thus frustration and dissatisfaction.
The most extensive and comprehensive research on detective work was completed
by Canadian criminologist Richard Erickson (1981), who wrote a book entitled Making
Crime: A Study of Detective Work. He studied detectives in Toronto, Ontario. Through
interviews, observations, and related analysis, Erickson provides a rich elaboration of
detective work in the context of organization, occupational environment, modus operandi, and ideology.
In the ranking of detective work, homicide detective work traditionally occupies the
highest status, followed by robbery and sexual assault detectives. This is because of the
fact that more serious crimes carry more social and moral significance. Therefore, more
resources are given to these types of crimes. As noted in the early book Detective Work:
A Study of Criminal Investigation (Sanders, 1977), homicide units generally have the
smallest workload and the highest clearance rate. At the other end of the detective
spectrum, property crime units (burglary and larceny) have the highest workloads and
lowest clearance rates.
Method
During the 2005-2006 academic year, the researcher visited both the Seattle and
Vancouver Police Departments numerous times, meeting with the respective homicide units. Both the Seattle and Vancouver homicide units have 18 officers. The
Seattle homicide unit consisted of three squads of six officers. Each squad has a
Sgt. and five detectives. The five detectives consist of two pairs who work together
plus a 5th wheel who investigates felony assaults and is periodically called to help
with a homicide. The Vancouver Homicide Squad is composed of two teams of
Reasons et al.
439
eight detectives each, with a Sgt. leading each team. As in Seattle, the officers work
in two person units.
In the Summer of 2005, prior to the extensive field work, a homicide interview
schedule was constructed based on previous research and the current researcher’s
interests. It included demographic information, opinions regarding homicide work,
views of the factors related to homicide, and opinions on the death penalty, among
other issues. From September through December 2005, interviews were conducted
with detectives in both Homicide Units. In Seattle, 16 of the 18 homicide officers were
interviewed, while in Vancouver, 14 were interviewed, for a total of 30 interviews of
homicide officers.
The interviews were conducted individually with each detective in a separate room
in the homicide unit. Each interview took approximately 1.5 hr although they varied
from 1 to 2 hr. The officers were assured anonymity and that identifying information
would be removed before data were distributed to others. On completion of the 30
interviews, a coding form was devised to provide more uniform data. The interviews
were coded and provided the following results.
Results
Detective Characteristics
The first general category of responses concerned the officer’s experience and characteristics. All detectives, except one in the Seattle unit, have at least 11 or more years of
police experience. In terms of time in the homicide unit, it is evident from Table 1 that
most detectives in both departments have 3 years or less experience, while the Seattle
homicide unit has a much larger number with 9 or more years. In terms of formal education, Seattle homicide detectives are much more likely to have a college/university
degree (75%) than Vancouver detectives (46%). Regarding their prior police experience,
homicide detectives disproportionately have been detectives in robbery or sex crime
units prior to homicide.
Working Environment
The next set of questions dealt with aspects of the job of the homicide detectives.
When asked why they applied to be homicide detectives, Table 2 shows that they realized it was the top of the heap in terms of detective investigation work. Seattle detectives
also emphasized that it was interesting and challenging, while Vancouver detectives
stressed they always wanted to go into it and there are more resources.
Table 3 provides their opinions on the best aspects of being a homicide detective.
In terms of the best aspects of the job, using one’s brain, and the challenge and excitement, were noted by half in both departments’ homicide units. Working through the
entire case and having the best resources and personnel were mentioned by at least a
40% average for both departments, while locking up bad guys was mentioned by about
440
Homicide Studies 14(4)
Table 1. Detective Characteristics
Years in the department
0-10 Years
11+ Years
Years in homicide
0-3 Years
4-8 Years
9+ Years
Education
High School
Some College/university
Complete College/university
Previous positions
Patrol
Robbery
Sex crimes
Strike force
Seattle
Vancouver
Combined
1-6%
15-94%
0-0%
14-100%
1-3%
29-97%
7-44%
4-25%
5-31%
7-50%
6-43%
1-7%
14-47%
10-33%
6-20%
0-0%
4-25%
12-75%
3-23%
5-31%
6-46%
3-10%
9-30%
18-62%
16-100%
5-31%
3-19%
0-0%
14-100%
6-43%
7-50%
6-11%
30-100%
11-37%
10-33%
6-20%
Vancouver
Combined
Table 2. Why Go Into Homicide?a
Seattle
Top of heap/peak of investigation
Interesting/challenge
Always wanted to
More resources
Other
8-50%
9-56%
4-25%
1-6%
7-44%
6-43%
3-21%
7-50%
4-29%
2-14%
14-47%
12-40%
11-37%
5-17%
9-30%
a. Many respondents gave more than one answer.
one fourth of detectives. There appears to be more satisfaction in the Seattle unit with
resources and overtime pay, compared to the Vancouver unit.
Regarding the worst aspects of the job, the Seattle unit noted the hours/pagers going
off in the middle of the night as the worst thing, while the Vancouver unit’s most frequent complaint is case failures due to “technicalities.” According to Table 4, another
noticeable difference is Seattle detectives were more likely to cite child victims as a
worst aspect of work, while Vancouver detectives noted strong personalities/egos.
When asked what are the most important skills for a homicide detective, both units
listed people skills as the top one, as shown in Table 5. Being organized and interviewing skills were next although these were noted more frequently by Seattle detectives. The next question dealt with the degree of dangerousness of being a homicide
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Reasons et al.
Table 3. Best Part of Working Homicidea
Seattle
Use Brain/exciting/challenging
Work through entire case
Best people and resources
Jail bad guys
Freedom/leadership
Overtime pay
Other
9-56%
6-38%
7-44%
4-25%
3-19%
3-19%
3-19%
Vancouver
7-50%
8-57%
5-36%
3-21%
3-21%
0-0%
4-29%
Combined
16-53%
14-47%
12-40%
7-23%
6-20%
3-10%
7-23%
a. Many respondents gave more than one answer.
Table 4. Worst Part of Working Homicide
Seattle
Hours/pagers
Case fails because of “technicalities”
Child victims
Strong personalities/ego
No lab
Other
9-56%
4-25%
4-25%
0-0%
0-0%
4-25%
Vancouver
3-21%
5-36%
1-7%
3-21%
1-7%
7-50%
Combined
12-40%
9-30%
5-17%
3-10%
1-3%
11-37%
Table 5. Most Important Skills as a Homicide Detectivea
Seattle
People skills
Organized
Interviewing skills
Detail skills
Patience
Writing skills
Tenacity
Flexibility
Other
8-50%
5-31%
6-38%
3-19%
2-13%
1-6%
0-0%
0-0%
8-50%
Vancouver
5-36%
3-21%
2-14%
1-7%
2-14%
2-14%
2-14%
2-14%
6-43%
Combined
13-43%
8-27%
8-27%
4-13%
4-13%
3-10%
2-7%
2-7%
14-47%
a. Many respondents gave multiple answers.
detective. As Table 6 shows, it is the least dangerous job in policing, while patrol is the
most dangerous according to homicide detectives.
The next question dealing with working conditions concerned the relationship with
the prosecutor/crown. This aspect of detective work is often overlooked by researchers,
442
Homicide Studies 14(4)
Table 6. Dangerousness
Seattle
Patrol most dangerous
Homicide least dangerous of police work
Strike force/ERT most dangerous
Other
Vancouver
Combined
9-64%
10-71%
2-14%
0-0%
22-73%
19-63%
2-7%
4-13%
13-81%
9-56%
0-0%
4-25%
Table 7. Relationship With Prosecutor/Crown
Seattle
Good
Not so good
Bad
Vancouver
13-81%
1-6%
2-13%
6-46%
5-38%
3-15%
Combined
19-65%
6-21%
5-14%
Table 8. The Clearance Rate for Homicide Has Decreased Over the Last Several Decades,
How Would You Explain That?a
Seattle
Legal rules/courts/technicalities
More organized/gang homicides
Stranger homicides
Other
1-6%
7-44%
5-31%
5-31%
Vancouver
Combined
12-86%
5-36%
0-0%
5-36%
13-43%
12-40%
5-17%
10-33%
a. Respondents gave multiple answers.
but is a significant part of their job. As observed in Table 7, the most frequent response
in both units was a good relationship; however, such a response was noted by significantly more Seattle homicide detectives.
Finally, research has indicated a decline in the clearance rate of homicide over the
last several decades in Canada and the United States. Homicide detectives were asked
how they would explain this decline. Nearly all of the Vancouver detectives identified
legal rules/courts/technicalities, whereas only one Seattle detective provided this
explanation in Table 8. The major factors identified by Seattle detectives were more
organized/gang homicides and stranger homicide. Vancouver detectives also noted
organized/gang homicides but not stranger homicides.
Factors/Causes of Homicide
The next series of questions dealt with the detectives’ opinions concerning the types of
factors that produce homicide. It is basically their views of the “etiology” of homicide.
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Reasons et al.
Table 9. Why Do You Think People Kill Each Other?a
Seattle
Emotional/anger/situational
Premeditated/planned/gang
Drugs/money
Criminal lifestyle
Other
13-81%
7-44%
5-31%
3-19%
6-38%
Vancouver
Combined
11-79%
7-50%
7-50%
0-0%
5-36%
24-80%
14-47%
12-40%
3-10%
11-37%
a. Respondents gave multiple answers.
Table 10. Factors Related to Homicide
Seattle
Inequality/poverty
Yes
13-81%
No
3-19%
Mental illness
Yes
12-75%
No
4-25%
Alcohol
Yes
14-88%
No
2-12%
Illegal drugs
16-100%
Yes
No
0-0%
Gangs
Yes
15-93%
No
1-7%
Race/ethnicity
Yes
15-94%
No
1-6%
Availability of guns—especially handguns
Yes
11-69%
No
5-31%
Vancouver
Combined
11-79%
3-21%
24-80%
6-20%
8-57%
6-43%
20-67%
10-33%
12-86%
2-14%
26-87%
4-13%
14-100%
0-0%
30-100%
0-0%
14-100%
0-0%
29-97%
1-3%
13-93%
1-7%
28-93%
2-7%
14-100%
0-0%
25-83%
5-17%
The first question was a general one, “Why do you think people kill each other?” As
evident from Table 9, the largest response was emotional/anger/situational, followed by
premeditated/planned/gang, and drugs/money. Next the homicide detectives were
asked if a number of factors were related to homicide. In Table 10, the responses are
noted by the respective factors. Over three quarters of detectives (80%). identified
inequality/poverty as a factor.
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Homicide Studies 14(4)
Table 11. Why Does the United States Have a Higher Rate and Canada a Lower Rate?a
Seattle
U.S. has more guns available
U.S. more violent historically & now via war etc.
More inequality in the United States
United States has more racism/racial conflict
Canadians more polite, not as uptight/driven
Less drug problems in Canada
Family Structure
Canada has better safety net
Other
6-35%
5-31%
4-25%
4-25%
1-6%
1-6%
3-19%
0-0%
5-31%
Vancouver
11-79%
4-29%
5-36%
3-21%
3-21%
3-21%
0-0%
2-14%
3-21%
Combined
17-57%
9-30%
9-30%
7-23%
4-13%
4-13%
3-10%
2-7%
8-27%
a. Respondents gave multiple answers.
Most detectives identified mental illness as a factor although it was more frequently
noted by Seattle detectives (75%) compared to Vancouver (57%). Detectives from both
departments estimated only about 5% of all homicides are related to mental illness.
Alcohol is identified by detectives in both departments as a primary factor in homicide.
Homicide detectives in both departments are unanimous that illegal drugs are a factor in
homicide. However, when explaining how illegal drugs affect homicide, they emphasize
the business/gang aspect, not the effects of the illegal drugs on individuals.
Detectives in both homicide squads identified gangs as a factor in homicides. However,
the proportion of homicides that are gang related has been declining since the mid-1990s
in Seattle, while increasing in Vancouver during the same period. Over 90% of detectives identified race/ethnicity as a factor in the gang involvement. The complexion of the
issue differs in each city. In Vancouver, where 49% of the population are people of color,
Asians are noted, while in Seattle it is African Americans followed by Asians.
The last factor addressed in Table 10 is availability of guns—especially handguns.
While all Vancouver homicide detectives believe this is a factor, only about two thirds
of Seattle detectives view this as a factor. In the next question, detectives were presented
with the fact that the homicide rate in Canada is one third that of the United States and
were asked to provide their opinion of why there is such a discrepancy. As Table 11
shows, gun availability is the top reason in both homicide units, but many more Canadian
homicide detectives (35%) cite this compared to American homicide detectives (28%).
Detectives in both departments are similar in noting the more violent nature of the United
States and the fact that there is more inequality in the United States than in Canada.
Vancouver detectives also identify that Canadians are more polite, have less of a drug
problem and a better safety net, while Seattle detectives identify Canadians having a better family structure.
Television, Homicide, and the Death Penalty
Since media crime and violence are popular, particularly in the United States, the next
question concerned the portrayal of homicide and homicide detectives in television
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Reasons et al.
Table 12. There Are a Lot of Crime Shows on TV and They Often Portray Homicide and
Homicide Detectives, Do You Think They Are Realistic?
Seattle
Yes
No
4-27%
12-73%
Vancouver
Combined
3-15%
11-85%
7-23%
23-77%
Table 13. Death Penalty as Deterrent and Death Penalty Support
Seattle
Death penalty as deterrent
Yes
2-13%
No
14-87%
Support the death penalty
15-93%
Yes
No
1-7%
Vancouver
Combined
3-21%
11-79%
5-17%
25-83%
8-57%
6-43%
23-77%
7-23%
crime shows. As Table 12 shows, the great majority of homicide detectives in both
departments view them as unrealistic.
Since Washington State, like most states, has the death penalty, whereas Canada and
most advanced industrial nations do not, the next question addressed the death penalty.
Although the detectives do not believe in the general deterrent effect of the death penalty, many support the death penalty. As per Table 13, homicide detectives in both
departments overwhelming do not view the death penalty as a general deterrent.
However, there is a major difference between the homicide units in terms of support for
the death penalty. Nearly all (93%) of Seattle detectives support it, while a slim majority (57%) of Vancouver detectives support the death penalty.
Discussion
The characteristics of homicide detectives in both departments were quite similar. They
have at least 10 years police experience and are disproportionately drawn from previous work in robbery and sex crimes. The only major difference was that the Seattle
homicide detectives were largely graduates of college/university (75%), compared to
their Vancouver counterparts (46%).Although homicide units portrayed on TV are
often diverse in terms of gender, race, and ethnicity, these units were made up of largely
White males. In the Vancouver homicide unit there were two women detectives and
one Black male detective. Although Vancouver is nearly half Asian, there were no
Asian homicide detectives. Asians, particularly East Indians, have a heavy involvement
in the drug/gang business and as offenders and victims of homicide. At the time of my
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Homicide Studies 14(4)
interviews, Seattle homicide unit had one Hispanic male detective, two Japanese
American male detectives, and one women detective. There were no African American
homicide detectives although nearly half of Seattle homicide offenders and victims are
African American. The Vancouver homicide detectives noted that language differences
often arise in their investigation although they point out that there are several officers
on the force who provide translation for them. Therefore, although the two cities are
diverse, particularly Vancouver, the homicide units are largely White male.
Our analysis of interviews with homicide detectives in Vancouver, British Columbia
and Seattle, Washington provides a window to the working ideology of these homicide
detectives. Their views and opinions were assessed in the following four areas (a) working environment, (b) causes of homicide, (c) television portrayal of homicide work, and
(d) the death penalty.
Working Environment
In terms of working environment, homicide detectives in both departments sought this
job because of its high status, better resources, interesting and challenging work. This
confirms previous research regarding homicide detectives as the most prestigious type
of detective, with fewer cases and more resources than other detectives. In terms of
departmental differences, Seattle detectives were more likely to note the interesting and
challenging nature of homicide work, whereas Vancouver detectives focused on the
fact of more resources.
The next part of the work environment addressed was the best and worst aspect of
being a homicide detective. The top response regarding the best aspect was working
through the entire case and having the best personnel and resources. There is more
satisfaction in the Seattle unit with resources and overtime pay than in the Vancouver
unit. In terms of the worst aspects of the job, Seattle detectives were most likely to state
the hours/pagers going off in the middle of the night. In both departments, certain detectives are on call/up for the next homicide and will receive the 3 a.m. call. Homicide, of
course, does not conform to an 8 a.m. to 5 p.m. work schedule. The most frequently
mentioned “bad” part according to Vancouver detectives was case failures due to “technicalities.” This is understandable, since Canada only recently passed a constitution
(1985) providing expanded rights to the accused similar to the U.S. Bill of Rights. It
takes several decades to settle case law regarding these rights and, as we know in the
United States, these rights change over time with case law. The Canadian Case law over
the last decade has tightened the “rules” of police, generally, and homicide detectives,
specifically. Another noticeable difference is Seattle detectives were more likely to cite
child victims as one of the worst aspects, whereas Vancouver detectives noted strong
personalities/egos. This reflects the fact that Vancouver has fewer small children as
victims than Seattle, while the Vancouver unit was undergoing a great deal of change in
leadership and much stress.
People skills were noted most frequently by homicide detectives as the most important skills needed for the job. This makes sense, since detectives must converse with
Reasons et al.
447
potential witnesses from all “walks of life,” victims’ families/friends/acquaintances/
patrol officers, forensic people, prosecutors, crime lab investigators, and suspects. As
one detective noted regarding suspects “never ask a person if they killed someone. It
is like a sales school, lead them to the car,” or another observed “you have to be nice
to child molesters/murderers and put aside your revulsion.” Being organized and interviewing skills were next most frequent although these were more likely mentioned by
Seattle detectives. Obviously these are significant abilities, given the amount of material, number of people, forms, contacts, and so on needed for each case.
One of the biggest myths perpetrated by television and other media is that being a
homicide detective is very dangerous. Homicide detectives rated their job as the least
dangerous in their police careers. As one said, “When you are called out to a homicide
scene it is the safest place on earth. You show up and the victim is dead, perp gone, and
ten cops with their hands in their pockets. Only danger is spilling hot coffee on yourself.” Most detectives noted that if they have a dangerous suspect to arrest, they would
use the SWAT squad or a similar unit. Thus, like the research shows, policing is a relatively safe occupation compared to others, such as construction, mining, and fishing,
and within policing, being a homicide detective is very safe (Kappeler & Potter, 2005).
When you look at the actual job of homicide detectives, about 80% of the job takes
place in the office, while only about 20% is being on the street, usually regarding witnesses, crime scenes, informants, courts, for example, and so on.
The relationship with the prosecutor/crown was the next question. This aspect of
detective work is often overlooked by researchers, but it is a key part of their job.
The most frequent response was a “good” relationship in both units, although, Seattle
detectives were significantly more satisfied than Vancouver detectives. This difference is largely due to their different social and legal environment. In Seattle, a new
program had been instituted in recent years whereby specific prosecutors are assigned
to a case from crime scene through trial. In Vancouver (and Canada) there is a tradition of more separation of the Crown and the police. Also, given the recent emergence
of more established Constitutional Rights for accused in Canada, Crown attorneys are
“policing” more carefully the work of homicide detectives. It appears that there is
less likely to be the continuity of a single Crown counsel from the homicide to arrest
to adjudication, as in Seattle.
Finally, success in homicide work is largely measured by clearance of cases, as part
of the work environment. Although homicide has the highest rate of clearances for
crimes, since the 1970s homicide clearance rates have declined in both the United
States and Canada. When asked their opinions on why this has occurred, Vancouver
detectives were most likely to cite legal rules/courts/technicalities, while only one Seattle
detective gave this response. The major factor noted by Seattle detectives was that there
were more organized/gang homicides and stranger homicides. Some Vancouver detectives noted organized gang homicides but not stranger homicide. The above noted
factors, types of legal changes, plus resources, police/prosecutor relationships, and
political environment may all play a role in clearance rates. (“Special Issue: Criminal
Justice Responses to Homicide,” 2007).
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Homicide Studies 14(4)
Causes of Homicide
Most people have a set of opinions (ideology) regarding why people commit crime
generally, and homicide, specifically. Of course, members of the criminal justice system also have a “professional ideology” regarding the causes of crime. When asked
the global question, “Why do you think people kill each other?” the large majority of
homicide detectives identified “emotional/anger/situational factors” as prominent.
This is the major reason for homicide cited by academics in both Canada (Gomme,
2002) and the United States (Miethe & Regoeczi, 2004). These motives are prominent
in homicide throughout the world. The next most frequent response was premeditated/
planned/gang homicide.
Homicide detectives identified a number of specific factors associated with the occurrence of homicides. Inequality/poverty was noted by the large majority of detectives.
As one Seattle detective observed, “When I was first in the department, I thought everyone could make it, but in poor neighborhoods there is a lack of direction, drugs and
alcohol.” According to a Vancouver detective, “It seems poor people do more risky
things in their lives to make ends meet, such as prostitution/theft/murder.” This structural factor has been identified as a cause of homicide by researchers around the world.
The majority of detectives in both cities identified “mental illness” with homicide in
about 5% of cases, with Seattle homicide detectives more frequently citing this cause.
According to one Seattle detective, “they get off meds and already have a drug problem,” while a Vancouver detective places this factor in a policy context, “Especially
since the 1990s when the Provinces closed beds, they go off meds and commit homicide and get killed by officers (suicide by cop).” While mental illness plays a relatively
small role in homicides, the media overemphasizes these few cases. (Kappeler & Potter,
2005). Since Canada generally, and Vancouver specifically, has a more adequate social
safety net, including mental health services, this might explain the more frequent
response by Seattle homicide detectives.
Drugs were identified by detectives in both departments as a major factor in homicide.
However, their casual relationship to homicide was distinguished by the detectives. The
legal drug alcohol was viewed as a primary factor in causing homicide due to the loosening of inhibition, bravado, anger, particularly in domestic and nightclub/party homicides. As one Seattle detective pointedly observed, “Yes, if there were no alcohol or
drugs we would be out of business.” In Vancouver, a detective relates that “it is significant, we get domestic and club shootings-drinking.” They all note that alcohol takes
away inhibitions, and brings out Machismo. Although all homicide detectives viewed
illegal drugs as a factor in homicide, their understanding of the casual relationship
differs from that of alcohol. In terms of illegal drugs, the large majority of homicide
detectives explain that they are related to the business/trade/market in illegal drugs,
not the physiological effect of illegal drugs. A Seattle detective summarizes this point,
“most homicides are related to traffic/trade, not caused by the effect of illegal drugs.”
In Vancouver, a homicide detective observes “it is the money making aspect-business
that leads to homicide-not taking drugs.” This difference has long been noted by
Reasons et al.
449
researchers. Alcohol is our most dangerous drug in terms of producing violence, generally, and homicide, specifically.
Gangs and race/ethnicity were identified by the large majority of homicide detectives as significant factors. Seattle detectives commented that gangs had decreased in
the past decade. This confirms United States national data (Miethe & Regeozi, 2004) In
Vancouver, while homicide rates have been decreasing over the last decade like Seattle,
the proportion of homicides that are gang related has been increasing since 2000. Since
2000, Vancouver has a much higher proportion of gang/drug homicide than Seattle
(Reasons, 2008).
Over 90% of detectives in both cities identified race/ethnicity as factors in homicide. This was also noted in terms of gangs being disproportionately made up of racial/
ethnic minorities. In Vancouver, Indo-Canadian (East Indian) and Chinese minorities
were noted, while in Seattle, Blacks were primarily identified, with Asians to a lesser
degree. As a detective in Vancouver noted, “Huge Indo-Canadian gang problem.” In
Seattle, where Blacks are about 10% of the population, they make up nearly half of the
victims and offenders in homicide cases. The relationship of race and class is in a
Seattle homicide detective’s observation “rates are higher in poor, black, minority
communities.” The Vancouver population is 49% visible minorities, compared to 18%
visible minorities in Seattle. Homicide offenders and victims are disproportionately
ethnic/racial minorities in Canada, United States, England, and other Western countries.
This largely is due to their being economically disadvantaged (Miethe & Regeoczi,
2004). Criminologists have long identified race/ethnicity and immigration with gangs
(Thrasher, 1925).
The last specific factor addressed was availability of guns, especially handguns.
Here we find a major difference between Vancouver and Seattle homicide detectives.
While all Vancouver detectives view this as a factor, only about two-thirds of Seattle
detectives had the same view. This undoubtedly reflects the fact that guns, particularly
handguns, are not easily available in Canada, consisting of less than 30% of the homicides. The history of the United States and the 2nd Amendment, the fact that the United
States has more guns in private citizens homes per capita than any other country in the
world, and that two thirds of homicides in the United States are by guns explains this
difference in the ”Ideology” of guns. The “taken for granted” nature of guns and the
ideology of guns and “self protection” and individualism, is not obvious to most people
in the United States, but those in other countries readily identify this as a cause of homicide in the United States.
In the last question concerning the “factors/causes” of homicide, the detectives were
cited the fact that the United States has 3 times the rate of homicide as Canada and
asked for their opinion why there is this difference. While gun availability is the most
identified factor in both homicide units, twice as many Canadian homicide detectives cite this compared to their American colleagues. Both homicide detective units
next point to the more violent history and the greater inequality in the United States.
International research shows a positive correlation between levels of firearm ownership and homicide rates (Dandurand, 1998). Inequality differences between Canada
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Homicide Studies 14(4)
and the United States and within each country is also a factor in homicide (Daly,
Wilson, & Vasdev, 2001). Generally, increased inequality coupled with perceptions
of illegitimacy in developed nations increases homicide rates (Chamblin & Cockran,
2006; Jacobs & Richardson, 2008).
Television and the Death Penalty
The large majority of homicide detectives believe television shows depicting homicide and homicide detective work are unrealistic. “The shows tend to ham up
dangerousness and glamour/CSI is totally distorted,” according to one Vancouver
detective. Homicide detectives spend about 80% of their time in the office, and
rarely draw, much less use, their weapon, and are not all young, attractive, and well
dressed as on TV. A Seattle detective observes that they are “generally unrealistic in
their portrayal of detectives.” The only show meriting some reality on both sides
of the border was Homicide: Life on the Streets, largely for the personalities and
interpersonal relations. As we already know from extensive research, the portrayal
of crime and criminal justice in the media generally, and on television specifically,
has little to do with the reality of crime and criminal justice (Kappeler & Potter,
2005; Surette, 2007).
While Canada abolished the death penalty in 1976, the majority of states, including
Washington, have the death penalty. The overwhelming majority of detectives in both
departments do not view the death penalty as a general deterrent. This is based on their
own experience that most homicides are situational/emotional and most killers do not
believe they will be caught. This, of course, is supported by a long line of empirical
research showing that death penalty is not a general deterrent.
However, there are major differences between the two cities when it came to support
for the death penalty. A slight majority of Vancouver detectives support it, while nearly
all Seattle detectives support it. Supporters from both departments view it in terms of
retribution. The nearly half of Vancouver homicide detectives who do not support the
death penalty noted that the state should respect life and the issue of wrongful convictions. The issue of wrongful conviction for murder has been documented in the United
States and in Canada.
Conclusion
The ideology (belief/opinions) of homicide detectives in Seattle, Washington and
Vancouver, British Columbia are generally similar. The only areas of major differences
concerned the role guns play in homicide and their views on the death penalty.
While availability of guns, particularly handguns, is singled out by homicide detectives as a factor in homicide by detectives in both cities, there is a major difference
in its significances. Only about two thirds of Seattle detectives cite this, while all
Vancouver detectives view guns as a major factor. This difference was further highlighted when they were asked to explain why the U.S. homicide rate is three times the
Reasons et al.
451
Canadian homicide rate. Twice as many Canadian detectives identified gun availably
as a significant factor compared to Seattle detectives.
Homicide detectives in both departments do not view the death penalty as a general deterrent. However, Seattle detectives overwhelmingly support the death penalty
as a form of retribution, while a slim majority of Vancouver detectives have this view.
Nearly half of Vancouver detectives are against the death penalty, citing respect for
life and wrongful convictions.
The similarities and differences found among homicide detectives in Seattle and
Vancouver reflect the nature of homicide work, the causes of homicide, police organizational characteristics, and the legal and cultural context of homicide.
Acknowledgment
The authors greatly appreciate the cooperation of the Seattle and Vancouver police departments,
particularly former Seattle Chief Gil Kerlikowski.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the authorship and/or
publication of this article.
Funding
The author(s) received no financial support for the research and/or authorship of this article.
References
Chamblin, M. B., & Cochran, J. K. (2006). Economic inequality, legitimacy, cross-national
homicide rates. Homicide Studies, 10, 231-252.
Daly, M., Wilson, M., & Vasdev, S. (2001). Income inequality and homicide rates in Canada and
the United States. Canadian Journal of Criminology, 43, 219-236.
Dandurand, Y. (1998) Firearms, accidental deaths, suicides and violent crimes: Ottawa, Ontario,
Canada: Department of Justice.
Erickson, R. V., (1981). Making crime: A study of detective work. Toronto, Ontario, Canada:
Butterworths.
Jacobs, D., & Richardson, A. M. (2008). Economic inequality and homicide in the developed
nations from 1975-1995. Homocide Studies, 12, 28-45.
Kappeler, V. F., & Potter, G. W. (2005). The mythology of crime and criminal justice (4th ed.).
Long Grove, IL: Waveland Press.
Kelleher, M. J. (2001, Winter). The professional ideology of social pathologists transformed:
The new political orthodoxy in sociology. American Sociologist, 32(4), 70-88.
Liazos, A. (1972). The poverty of the sociology of deviance: Nuts/ sluts/ and perverts. Social
Problems, 20, 102-120.
Miethe, T., & Regoeczi, W. C. (2004). Rethinking homicide. Cambridge, U.K.: Cambridge
University Press.
Miller, W. B. (1973). Ideology and criminal justice policy: Some current issues. Journal of
Criminal Law and Criminology, 64, 141-162.
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Mills, C. W. ( 1943). The professional ideology of social pathologists. American Journal of
Sociology, 49, 165-180.
Quinney, R. ( 1970). The social reality of crime. Boston: Little, Brown.
Radzinowicz, L. (1966). Ideology and crime. New York: Oxford University Press.
Reasons,C. (2008). A tale of two cities: Homicide in Seattle, Washington and Vancouver, British
Columbia. Criminal Law Quarterly, 54, 104-129.
Sanders, W. (1977). Detective work. New York: Tree Press.
Special Issue: Criminal Justice Responses to Homicide. (2007). Homicide Studies, 11, 79-164.
Surette, R. (2007). Media, crime and criminal justice (3rd ed.). Belmont, CA: Thomson
Wadsworth.
Thrasher, F. M. (1927). The gang. Chicago: University of Chicago Press.
Walker, S., & Katz, C. (2008). The police in America (6th ed.). New York: McGraw-Hill.
Bios
Charles E. Reasons is professor and chair of the Department of Law and Justice at Central
Washington University. He received his PhD in sociology from Washington State University in
1972 and his LLB in 1992 from the University of British Columbia Law School. He practiced
law in Vancouver, British Columbia in the 1990s. He has published nine books and scores of
articles and book chapters on social and legal problems in the United States and Canada, while
teaching in both countries.
David Kim just completed his MS degree in criminal justice at Washington State University
and is working in Olympia, Washington. He is a 2007 graduate of the Department of Law and
Justice at Central Washington University.
Teresa Francis is an assistant professor in the Department of Law and Justice at Central
Washington University. She is a lawyer with a JD from Mississippi College School of Law and
an LLM specializing in criminal law from the State University of New York at Buffalo School
of Law. She specializes in criminal and civil law and procedure, family law, and correctional law.
Running Head: RESEARCH PROPOSAL
1
Research Proposal
Erica Murillo, Nathan Priest
CJS/345
10/11/2018
Mr. Swanson
RESEARCH PROPOSAL 1
2
Introduction
The homicide side of the criminal and justice department has always been one full of
highlights and controversies. It is among the departments that are focused on how the average
civilian leads his life and in the case of a crime how everything rolls out. Many of the issues in
the homicide department have always been because of the lack of understanding among the
people involved. This paper will aim at explaining exactly which role understanding and
negotiation can play in minimizing these cases.
It is important to study this area because of the number of cases that have been
forwarded in the recent past. It is to the common interests of the average civilian to live a life that
is peaceful and crime free. This is why it is of utmost importance to study this area of the
criminal and justice unit.
The homicide department can solve these problems if it is equipped with the necessary
personnel and left to do its work without the frequent overlapping of roles in the criminal and
justice unit. There have been cases where something occurs, and it becomes bold clear that this is
where the homicide department can come and perform its duties. To their shock, they do find the
Sherriff’s office and the FBI already on the scene. At times even remote federal units report to
RESEARCH PROPOSAL 1
3
the same scene making the homicide faction look lost and out of place in a role that was
primarily supposed to be theirs.
The homicide department has also not been serviced with resources and personnel like
other departments of the criminal and justice departments. It is for this reason that those in the
homicide department have had to do with the little resources and limited personnel they have at
their disposal. Were they provided with the amount of resources they need on a day to day basis
and have their personnel duly trained, they would be the most efficient unit and this would go a
long way to even transform the entire criminal and justice department and through all that make
the life of an average civilian as smooth and safe as possible.
If they are given what they want, we will witness a drastic change in how crime is
handled in our societies. The frequent overlapping of roles where even the FBI get caught up in
duties which were supposed to be homicide would not be happening. Through that, we would
have an active and working criminal and the justice system. This will translate to the provision of
better services to the average civilian in any part of the country.
When personnel in this department are duly and thoroughly trained, they would have
skills that match the demand of the job they are given and mandated to do. There is no difficult
task to do in this world; a task is only difficult to do if the person doing it is not aware or sure of
what they are supposed to be doing in the first place. When they have the appropriate skills,
these personnel will always walk into the toughest of all situations and apply a high and
respected level of professionalism. This is what all civilians hope for and want from the criminal
and justice department(Chen et al., 2018).
RESEARCH PROPOSAL 1
4
If these recommendations are not put to action, and the homicide department continues
to get sidelined, it is the average civilian that feels the pinching more than any other person. All
departments and units are there at the service of the civilian, and it only makes sense if they act
according to the desires and the preference of the average civilian.
When the personnel are not trained well, they will always approach some scenes, and
because of how untrained and unaware they are, they fail to handle the situations in the best way
possible making the affected parties not feel the bits of their service. Untrained personnel will
end up compromising more than even making things in order. To avoid such scenarios, it only
makes sense if they get rained to the last bit of knowledge and practice.
When they also don't get the resources they call for, they wouldn't be able to do their
work efficiently. In some cases, they will have to fill in details that are not tested at all, and this
will lead to a lot of flaws in their artistry. The department has also benefitted at all from the
sidelining it receives from time to time and being overlooked too.
RESEARCH PROPOSAL 1
5
References
Chen, X., Zhang, X., Wong, S. C. P., Yang, M., Kong, D., & Hu, J. (2018). Characteristics of
alleged homicide offenders with and without schizophrenia in Sichuan, China. Criminal
Behaviour and Mental Health. https://doi.org/10.1002/cbm.2054
J Quant Criminol (2014) 30:453–483
DOI 10.1007/s10940-013-9210-5
ORIGINAL PAPER
Immigration and the Changing Nature of Homicide in US
Cities, 1980–2010
Graham C. Ousey • Charis E. Kubrin
Published online: 15 October 2013
Springer Science+Business Media New York 2013
Abstract
Objectives Previous research has neglected to consider whether trends in immigration
are related to changes in the nature of homicide. This is important because there is
considerable variability in the temporal trends of homicide subtypes disaggregated by
circumstance. In the current study, we address this issue by investigating whether withincity changes in immigration are related to temporal variations in rates of overall and
circumstance-specific homicide for a sample of large US cities during the period between
1980 and 2010.
Methods Fixed-effects negative binomial and two-stage least squares (2SLS) instrumental variable regression models are used to analyze data from 156 large US cities
observed during the 1980–2010 period.
Results Findings from the analyses suggest that temporal change in overall homicide and
drug homicide rates are significantly related to changes in immigration. Specifically,
increases in immigration are associated with declining rates for each of the preceding
outcome measures. Moreover, for several of the homicide types, findings suggest that the
effects of changes in immigration vary across places, with the largest negative associations
appearing in cities that had relatively high initial (i.e., 1970) immigration levels.
Conclusions There is support for the thesis that changes in immigration in recent decades are related to changes in rates of lethal violence. However, it appears that the relationship is contingent and varied, not general.
Keywords Homicide Immigration Violent crime trends
Fixed-effects models
G. C. Ousey (&)
Department of Sociology, College of William and Mary, Williamsburg, VA, USA
e-mail: gcouse@wm.edu
C. E. Kubrin
Department of Criminology, Law and Society, University of California, Irvine, Irvine, CA, USA
e-mail: ckubrin@uci.edu
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Introduction
In April 2007, the National Research Council of the National Academies convened a
distinguished panel of scholars with expertise in sociology, criminology, law, economics,
and statistics to address issues underlying the study of crime trends in the United States.
Participants identified key substantive and methodological issues related to studying crime
trends and discussed ways to improve understanding of both shorter- and longer-term
changes in crime. Findings from their studies were published in the volume, Understanding
Crime Trends (Goldberger and Rosenfeld 2008). While the volume covers a diverse
assortment of issues, notable among the omitted issues is the ‘‘impact of immigration,’’
which according to the volume editors ‘‘requires much more extensive evaluation’’
(Rosenfeld and Goldberger 2008:3).
Since the publication of the NRC volume, scholarship on the effects of immigration on
crime trends has become more common. Indeed, several recent longitudinal studies have
investigated the relationship between immigration and violence across US metropolitan
areas, cities, and neighborhoods (MacDonald et al. 2013; Martinez et al. 2010; Ousey and
Kubrin 2009; Stowell et al. 2009; Wadsworth 2010). Each of these studies provides some
evidence in support of the thesis that increased immigration is associated with decreased
rates of violent crime.
Yet there is still much to be learned about the impact of changes in immigration on
trends in violence, particularly homicide, in the US. In particular, previous research has
neglected to consider whether trends in immigration are related to changes in the nature of
homicide. This is an important limitation because while overall homicide rates have been
trending steadily downward in recent decades, there is considerable variability in temporal
trends of homicide rates disaggregated into subtypes based upon circumstances or motives.
For instance, the rate of argument homicide, traditionally the most common subtype, has
fallen steadily since at least as far back as 1980. In contrast, drug- and gang-related killings
have exhibited periods of both upward and downward growth in recent decades. To the
extent that these homicide subtypes reflect the ‘‘nature’’ of this form of lethal violence,
there have been noteworthy changes that warrant explanation.
Previous research suggests there are differences in the effects of some covariates on
homicide rates disaggregated by circumstance or motive (Block 1993; Block and Block
1992; Cornell et al. 1989; Goldstein et al. 1992; Harries 1993; Kubrin and Ousey 2009;
Mears and Bhati 2006). Included in this literature are a handful of studies that have
identified differences in the effects of immigration on circumstance-specific homicide
subtypes (Kubrin and Ousey 2009; Nielsen et al. 2005). Unfortunately, the evidence in
these studies is drawn entirely from cross-sectional research. Consequently, it does not
advance our understanding of recent trends in homicide subtypes or of the connection
between such trends and changes in immigration. To accomplish that objective, longitudinal research that specifically investigates the pattern and predictors of over time changes
in circumstance-specific homicide rates is needed.
In the current study, we address this need by investigating the temporal variation in
homicide rates for a sample of large US cities. Our analyses build on the current research
literature on homicide trends in several ways. First, while prior studies have focused
primarily on trends in overall homicide rates, we extend that work by also examining time
trends in several circumstance-specific homicide rates (e.g., argument, felony, drug-related
and gang-related). Second, we address limitations of the small but growing literature on the
longitudinal relationship between immigration and violence. Prior studies have examined
this relationship across multiple decades within a single city (Martinez et al. 2010) or have
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observed changes across multiple places (e.g., cities or metro areas) within a single decade
(Stowell et al. 2009; Wadsworth 2010). We extend this work by examining the longitudinal
association between immigration and homicide in more than 150 large cities over a 30-year
period spanning 1980–2010. We also advance previous research by investigating the
possibility that the longitudinal immigration-homicide relationship may vary across city
contexts. To wit, we draw lessons from a literature on ‘‘context of reception’’ (Portes and
Rumbaut 2006) and consider whether the effect of changes in immigration on homicide—
both overall rates and circumstance-disaggregated rates—varies across cities as a function
of differences in their preexisting levels of immigrant concentration. Finally, following
recent work by MacDonald et al. (2013), we consider the possibility that immigration may
be endogenous to homicide rates and we implement instrumental variables methods that
address their simultaneity.
Our study draws from and contributes to several bodies of criminological research
including trends in violence, homicide disaggregation, and the immigration-violence
nexus. For this reason, we begin the following section with a brief discussion of relevant
research themes from each of these areas. We follow that with information on the sample,
data sources, measures, and analytic methods utilized in our study. Next we present and
discuss the results of our statistical analyses. We conclude with a section that highlights the
implications of our results for subsequent theoretical and empirical work in the aforementioned areas of inquiry.
Conceptual Framework
Trends in Violence
Crime rates in the US have exhibited marked fluctuations over the past 30–40 years. In
particular, rates of homicide and robbery peaked in the 1980s and early 1990s, before
dropping by over 40 % through the end of the century (Blumstein and Rosenfeld 2008).
After declining or remaining stable for over a decade, evidence suggests that rates of
violence may be on the rise again in some large cities.
Attempts to understand these trends have generated renewed interest in dynamic and
longitudinal models of crime and violence (Greenberg 2010). This is evident not only in the
focus of the National Academies panel described earlier but also in the veritable explosion
of research on the crime drop in the US. For at least the last decade, criminologists have
worked diligently to identify the factors associated with the decline. Explanations abound,
ranging from the strong economy of the 1990s, to changing demographics such as the aging
of the baby boomers, to better policing strategies, to stricter gun control laws, to record
levels of imprisonment, to receding crack-cocaine markets, and even to increased immigration—the focus of the current study (Blumstein and Wallman 2006; LaFree 1999; Levitt
2004; Rosenfeld 2002; Wadsworth 2010; Zimring 2007).
In the context of the current study, several important conclusions may be derived from
recent research on crime trends. First, as Zimring (2007:195) suggests, there is not one
single cause that produced the declines in crime rates; instead, it is likely a combination of
factors working in concert. Second, Blumstein and Rosenfeld (1998, 2008) and Blumstein
et al. (2000) argue that trends in violence, including the dramatic rise in homicide in the
latter half of the 1980s and the subsequent drop in the 1990s, are best understood by
looking beyond aggregated rates and examining trends in age-, sex- and race-specific rates.
For example, they show the increase in homicide during the late 1980s was due to
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escalating violence among juveniles and young adults, predominantly (although not
exclusively) by and against black males, particularly in larger cities, and exclusively
involving handguns (Blumstein and Rosenfeld 1998:1207). They also show that the recent
decline in violence applies primarily to certain populations: ‘‘… the departure of young
people from the crack markets combined with the continuing decline of violence by the
over-30 population were major factors contributing to the steady decline in violent crime
from about 1993 until 2000’’ (Blumstein and Rosenfeld 2008:17). Finally, crime trend
studies highlight the fact that national-level trends often obscure important variations in
trends at more localized levels (Blumstein and Rosenfeld 2008:28). Stated alternatively,
the crime decline was not equally experienced across metropolitan areas, cities, neighborhoods, and even street segments—a point that is also true for crime booms and busts
more generally. Indeed, several studies show there is heterogeneity in crime trends across
cities, neighborhoods, and street segments (Kikuchi and Desmond 2010; McCall, Land,
and Parker 2010; Messner et al. 2005; Weisburd et al. 2004).
As this brief review of the literature reveals, significant progress has been made in terms of
documenting recent trends in aggregate crime rates as well as identifying important variations
in trends that appear when crime data are disaggregated. Progress also has been made in
accounting for variation in trends across multiple levels of analysis, with several macro-social
factors found to be associated with these crime trends. However, we identify two important
questions that remain unanswered in the crime trends literature. The first is related to whether
the nature or composition of violence has changed over time: does one pattern of temporal
change characterize all homicide motive/circumstance subtypes or does the direction and rate
of growth differ for some types relative to others? The second question addresses the extent to
which immigration matters for understanding trends in different homicide subtypes: are
changes in circumstance/motive-specific homicide rates over recent decades related to
changes in immigration? At present, we are unable to answer these questions because, by and
large, longitudinal studies have not disaggregated homicide rates by motive or circumstance.
Moreover, with few exceptions which we discuss below, longitudinal studies have not
examined changes in immigration as they relate to over-time changes in violence, omitting a
potentially important causal factor. These limitations are somewhat surprising because as we
also discuss below, there exists a substantial research literature that investigates predictors of
disaggregated homicide rates as well as a rapidly-growing body of literature on the longitudinal connection between immigration and crime.
Disaggregating Homicide
One of the most important findings to emerge from the homicide research literature is that
homicide is a multidimensional phenomenon (Miethe and Regoeczi 2004; Zahn 1991:17).
Homicides vary substantially in terms of motive, characteristics of the victim and offender,
setting, and circumstances. One of the earliest attempts to systematically categorize
homicides into conceptually meaningful categories is found in Marvin Wolfgang’s (1958)
classic study, Patterns in Criminal Homicide. In the first-ever analysis of a comprehensive
homicide dataset, Wolfgang analyzed nearly 600 homicide events in Philadelphia between
1948 and 1952, studying case characteristics in more detail than had any previous research.
Motivated in part by the results of Wolfgang’s study, scholars have increasingly argued
that homicides are not a homogeneous group. Rather, there are different types of homicides
with potentially distinct patterns, correlates, and causes (Flewelling and Williams 1999).
Consequently, there has been an expansion in the number of studies that attempt to identify
factors related to separate homicide ‘‘types.’’
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Despite a general movement towards disaggregation, scholars have not settled on
one particular classification strategy to serve all purposes. Indeed, some have focused
on differences in the victim-offender relationship (Decker 1993; Parker 2001; Parker
and Smith 1979; Parker and Toth 1990; Riedel and Przybylski 1993; Rodriguez and
Henderson 1995; Rojek and Williams 1993), others on differences in motive (Block
1993; Block and Block 1992; Cornell et al. 1989; Goldstein et al. 1992; Harries 1993;
Kubrin and Ousey 2009; Mears and Bhati 2006), and still others focus on the circumstances of the homicide event (Harries 1993; Goldstein et al. 1992; Papachristos
2009; Pyrooz 2012; Rosenfeld et al. 1999). Other studies develop homicide subtypes on
the basis of particular theoretical frameworks or empirical methods. For example, in
their study of homicide rates across US cities, Williams and Flewelling (1988) create a
theoretically integrated model combining social disintegration, resource deprivation, and
violent cultural orientation perspectives, which guides the calculation of disaggregated
rates. And Kubrin (2003) uses cluster analysis to classify homicide subtypes using
detailed victim, offender, and event information on over 2,400 homicides in St. Louis
from 1979 to 1995. Finally, focusing on the homicide situation (i.e., the nexus of
offender, victim, and offense characteristics in time and space) as the unit of analysis
and using qualitative comparative analysis, Miethe and Regoeczi (2004) examine
several data sources including Supplemental Homicide Reports from 1976 to 1998 and
state- and city-level police data to determine the empirical distribution of homicide
over three decades.
A discussion of the detailed findings from this literature is beyond the scope of the
current study. However, three important themes have emerged that are directly relevant
to our purposes. First, evidence indicates that some factors (e.g., concentrated disadvantage) exhibit effects that extend across many homicide subtypes whereas others
(e.g., residential instability) may affect a more limited set of specific types (e.g.,
Kovandzic et al. 1998; Kubrin 2003; Parker 1989). Thus, the correlates (and their
attendant theoretical explanations) of homicide subtypes may be different. Second,
researchers know much more about what predicts between-city variation in homicide
subtypes than they do about what explains within-city changes in type-specific rates.
This is because there are few studies that have examined change in the nature of
homicide over time within geographic units (cf., Miethe and Regoeczi 2004). Third,
although findings from a burgeoning literature suggest that measures of immigration
may be among a select group of ‘‘structural covariates’’ that consistently predict
changes in aggregate rates of violence, that placement would be premature because to
our knowledge there is much that is unknown about the generality of the immigrationviolence relationship, including how immigration affects over-time changes in specific
homicide subtypes.
In sum, the research literature on homicide subtypes underscores the importance of
considering disaggregated homicide rates. Studies reveal that the effects of some
explanatory variables exhibit broad ranging effects across many homicide categories
whereas others may be limited to specific types. However, this literature also exhibits two
important gaps that are relevant for the current study. First, with few exceptions—for
example, Kikuchi and Desmond (2010) and Kubrin and Herting (2003), both of which are
neighborhood-level studies—the vast majority of this research is cross-sectional. And
second, nearly all of the studies except two (Kubrin and Ousey 2009; Nielsen et al. 2005)
exclude immigration as an important potential correlate, despite research suggesting that
immigration is related to violence, a point which we discuss below.
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Immigration and Violence
Historically, immigrants have disproportionately taken the blame for many of society’s
problems, including crime. Yet a substantial literature has documented that immigrants are
less, not more, crime prone than their native-born counterparts. Studies repeatedly show
that immigrants are less likely to be involved in, or institutionalized for, crime compared
with those who are native born. In fact, the consistency of this finding prompted Martinez
and Lee (2000:496) to conclude: ‘‘The major finding of a century of research on immigration and crime is that… immigrants nearly always exhibit lower crime rates than native
groups.’’
Compared to a sizable literature on the individual-level association between immigrant
status and criminal offending, ‘‘there exists a comparative shortage of research on the
macro-level relationship between immigration and crime rates’’ (Ousey and Kubrin
2009:447–448). But prompted perhaps in part by Robert Sampson’s (2006) New York
Times op-ed which links declining crime rates of the 1990s to increased immigration, the
field has recently witnessed a proliferation of macro-level research on this topic (see Ousey
and Kubrin 2009:453–457 for a summary of aggregate-level studies on the immigrationcrime relationship). Ironically, the vast majority of these studies are cross-sectional; thus,
there remains a dearth of longitudinal research on the immigration-crime nexus. This
shortage of longitudinal research is a serious limitation because immigration is a dynamic
process whose effects unfold over time within places (Ousey and Kubrin 2009:448).
Indeed, many of the most important questions are centered on the issue of what will happen
to crime rates within a given place as it experiences an expansion or contraction of its
immigrant base. Questions such as these are about within-place temporal processes and
therefore can only be answered with a longitudinal framework that observes how immigration and crime vary within-units (e.g., cities) over-time. Assuming that between-place
(cross-sectional) relationships accurately reflect within-place (longitudinal) relationships is
risky, at best. Indeed, it is not unusual to find that between-unit and within-unit effects
operate in opposite directions (Curran and Bauer 2011; Phillips 2006a; Wadsworth 2010).
There are some notable exceptions to the claim that immigration-crime research is
primarily cross-sectional (MacDonald et al. 2013; Martinez et al. 2010; Ousey and Kubrin
2009; Stowell et al. 2009; Wadsworth 2010). Two of these studies, in particular, examine
the immigration-crime nexus in the context of understanding how immigration may have
contributed to the crime drop. Using time-series techniques and annual data for metropolitan areas from 1994 to 2004, Stowell et al. (2009) assess the impact of changes in
immigration on changes in violent crime rates. In line with Sampson’s claim, they find that
violence tended to decrease as metropolitan areas experienced gains in their concentration
of immigrants.
In a somewhat similar analysis conducted at the city-level, Wadsworth (2010) evaluates
the influence of immigration on city-level crime rates from 1990 to 2000. His analyses
include cross-sectional models that examine the between-city relationship between
immigration and rates of homicide and robbery in 1990 and 2000, respectively, and fixedeffects models that examine how within-city changes in immigration over the decade
influenced changes in homicide and robbery over that time period. Results from his
analyses are not entirely consistent but in general, it appears that in the cross-sectional
analyses, cities with higher levels of foreign-born residents have higher homicide and
robbery levels. Results from the longitudinal models, however, indicate that cities with the
largest increases in immigration experienced the greatest decreases in homicide and
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robbery. These findings illustrate our previous point that assuming the equivalence of
cross-sectional and longitudinal effects of immigration is unwise.
Although not focused on estimating immigration’s contribution to the crime drop,
Ousey and Kubrin (2009) investigate the impact of changes in immigration on changes in
violent crime for 159 US cities from 1980 to 2000. In line with Stowell et al. (2009) and
Wadsworth (2010), their study reports that on average, cities that experienced increases in
immigration experienced decreases in violent crime rates. Moreover, it also indicates that
immigration lowers violent crime by bolstering the prevalence of two-parent family
structures. A related study by Martinez et al. (2010) explores the effects of immigration on
neighborhood-level homicide trends in San Diego, California over the same time period.
Consistent with the studies just reviewed, their results show that the increasing foreignborn population reduced lethal violence. Finally, MacDonald et al. (2013) investigate the
extent to which immigrant concentration is associated with reductions in neighborhood
crime rates in the city of Los Angeles between 2000 and 2005. Once again, consistent with
extant research, they find that greater concentrations of immigrants in LA neighborhoods
are linked to significant reductions in crime, even after accounting for the non-random
selection of immigrants into L.A. neighborhoods.
Immigration and Homicide Subtypes: Theoretical Implications
While the preceding studies are valuable, they also are limited because none considers the
impact of immigration (or other covariates) on specific types of lethal violence. This
limitation is important because studying homicide subtypes can provide important insights
into a key theoretical question: How general is the relationship between immigration and
violence? At present, the most prominent scholarly explanations of the immigration-crime
association emphasize two alternative theoretical perspectives: social disorganization and
immigrant revitalization. The former asserts that immigration is a disruptive force that
breaks down collective social control leading to a positive association between immigration and violence. Moreover, this framework conceives of immigration’s effects in general
theoretical terms. This means that criminogenic effects are expected to be similar across
different forms of crime, including different homicide types (Nielsen et al. 2005). The
revitalization perspective, in contrast, suggests that immigration yields protective effects
that should lower rates of homicide. However, a review of scholarship invoking this
framework is unclear on whether it should yield general effects that are similar across
crime types or whether its effects should be more salient for some types of offending than
for others. Some discussions imply that immigration lowers crime generally by increasing
social integration and collective social control. But others seem to suggest that immigration
may help improve particular aspects of social life. For instance, immigration may benefit
the local economy by providing local businesses with a hard-working but low-cost labor
supply or by increasing employment growth as immigrant-owned startup companies proliferate. If the latter imagery is correct, it seems reasonable that the most prominent impact
of immigration may be to temper economically-motivated violence, such as homicides
committed during the course of other felonies (e.g., robberies) or as part of involvement in
the illegal drug trade, with much weaker effects expected for other subtypes, such as
argument-related killings. Alternatively, if the former depiction of the theory is accurate,
there is little reason to expect noteworthy differences in the expected effects of immigration on homicide subtypes.
To our knowledge, there are only two prior studies that examine the differential impact
of immigration on homicide subtypes. First, in a neighborhood-level study of black and
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Latino homicides in Miami and San Diego (Nielsen et al. 2005), Nielsen and her colleagues disaggregate a decade’s worth of homicides into several motive subtypes including
escalation, intimate, robbery, and drug-related motives. Findings from their analyses show
that recent immigration is negatively or not associated with most subtypes but is positively
associated with some instrumental killings (e.g., African-American drug-related homicides
in San Diego). Second, in a city-level study Kubrin and Ousey (2009) report somewhat
similar findings with respect to immigration’s impact on specific types of lethal violence.
Using Supplementary Homicide Report data from 2000 to 2002, Kubrin and Ousey (2009)
compute measures of argument, felony, drug-related, and gang-related homicides. They
find that cities with greater levels of immigrant concentration generally have lower rates of
all homicide types, but they also note evidence of a significant and fairly strong positive
relationship between immigration and gang-related killings. Viewed together, findings
from these studies bolster the possibility that immigration may have differential effects on
homicide subtypes. Consequently, they suggest that theoretical mechanisms that link
immigration and homicide may be specific and varied, rather than general and uniform. Yet
evidence from Nielsen et al. (2005) and Kubrin and Ousey (2009) must be regarded as
preliminary because these studies, like so many others in the immigration-crime literature,
are cross-sectional. Consequently, they do not address the central question of whether
within-place changes in immigration may (differentially) affect changes in particular
subtypes of homicide.
Finally, in addition to the shortage of longitudinal research on immigration and
homicide, particularly homicide subtypes, prior research has given little attention to one
other important issue: whether the effect of immigration on lethal violence varies across
places. Conceptually, there is good reason to expect such variation. Portes and Rumbaut
(2006), for example, suggest that different cities provide varying ‘‘contexts of reception’’
for immigrants. Some cities are well-established immigrant destinations that have ethnic
enclaves equipped with developed economic and social institutions that allow them to
effectively provide benefits to, and derive benefits from, new waves of immigration. It is in
these kinds of places, we argue, that immigration is most apt to provide a crime-constraining benefit. Alternatively, newer destinations may have a limited preexisting immigrant base and are likely to lack the economic and social organization to efficiently
integrate and incorporate new arrivals, resulting in short-term instability or disruption
rather than improved economic vitality and social cohesion. In these latter places, then,
increased immigration is less likely to result in a reduction of violence. A handful of
studies have begun to evaluate whether the effects of immigration on violent crime may
vary across places as a result of differences in their preexisting social context (e.g.,
Shihadeh and Barranco 2010; Velez 2009). Most notably, findings support the idea that the
immigration-crime relationship differs across ‘‘new destination’’ and ‘‘established/old
destination’’ places (Shihadeh and Barranco 2010). However, in addition to being few in
number, these studies are cross-sectional. Consequently, they do not allow us to discern
whether within-place, over-time growth in immigration affects temporal changes in total
and circumstance-disaggregated homicide rates differently depending on preexisting
context of reception that characterized a place.
In sum, findings from longitudinal studies on the immigration-crime nexus offer
noteworthy support to the argument that changes in immigration are associated with
declining crime rates, underscoring the importance of including this factor in aggregatelevel studies of crime in general, and violence in particular. Still, only a handful of studies
exist and those that do leave important questions unanswered. Indeed, despite both conceptual and empirical reasons for doing so, most prior studies have not disaggregated
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homicides into subtypes to determine how changes in immigration may be differently
related to changes in these forms of lethal violence. Moreover, no previous studies have
considered whether the aforementioned longitudinal relationships between immigration
and homicide rates (total and subtypes) vary depending on a city’s initial context of
reception.
Data and Methods
Units of Analysis
The current study focuses on US cities that have minimum populations of 100,000 residents in 1980, 1990, 2000, and 2010. In total, 156 cities meet these criteria and have
available data for at least one of the time points. The complete sample of city-year
observations used in our analyses is 591.1
Dependent Variables
The dependent variables include the overall city homicide rate as well as rates for each of
four homicide subtypes. To generate these rates, we first obtained counts of homicide from
the Supplementary Homicide Report (SHR) dataset compiled by the FBI as part of the
Uniform Crime Report. For each time point, we computed the relevant count by summing
3 years of homicide data. To compute ‘‘1980’’ homicide counts, we summed counts from
1979 to 1981; for ‘‘1990’’ counts, we used 1989–1991 data; for ‘‘2000’’ counts we used
1999–2001 data, and for ‘‘2010’’ we used 2008–2010.2
The first subtype is argument homicides. These include homicides that are classified as
having resulted from lover’s triangles, arguments over money, brawls that erupt among
participants under the influence of drugs or alcohol, and other arguments. Second, felony
homicides include cases in which a murder occurs during the course of another felony such
as a robbery, burglary, or rape. Drug-related homicides occur during actions that violate
narcotics laws (e.g., buying/selling/distributing illegal drugs). Gang-related homicides
refer to incidents with circumstances classified in the SHR dataset as a ‘‘gangland killing’’
or ‘‘youth gang killing.’’3
In an earlier version of our analysis, we estimated models in which homicide cases
with unknown circumstances were treated as a separate ‘‘unknown’’ homicide subtype
category. However, an anonymous reviewer noted that it was difficult to assess meaning
and interpret results regarding this unknown subtype category. After further consideration, we decided to eliminate the unknown subtype model results. Consequently, the
subtype analyses presented below utilize only the homicide cases for which circumstances are known. However, to evaluate whether our findings and conclusions regarding
the homicide subtypes are sensitive to whether unknown circumstance cases are included
1
Because some cities have missing data for one particular time point but not others, the number of valid
city-year observations (591) is somewhat less than the number of cities multiplied by the number of time
points (i.e., N 9 T = 156 9 4 = 624).
2
The 2010 SHR data were the most recently available when our analyses were initially conducted.
3
Some prior research distinguishes between gang-affiliated and gang-related homicides (e.g., Rosenfeld
et al. 1999). While we acknowledge that such a distinction may be relevant, unfortunately, the SHR data do
not allow us to make such a distinction.
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or excluded, we re-estimated our main models using twenty ‘‘complete’’ datasets in
which missing homicide circumstance codes were imputed via the chained equations
imputation routine (‘‘mi impute chained’’) in Stata version 12. Findings from the analyses of the imputed datasets are essentially identical to those reported herein and are
available from the first author upon request. The specific SHR homicide circumstance
codes that we included in each of the homicide subtypes described above are reported in
‘‘Appendix 1’’.
The use of SHR homicide data has been the focus of an important debate in the
homicide research literature. In particular, some researchers have questioned the
extent to which the value of these data is dampened by incomplete and missing
information, especially related to offenders, victims, and motive or circumstance (Fox
2004; Maxfield 1989). A related body of literature has debated methods of adjusting
homicide rates to accommodate missing data (see, for example, Flewelling 2004; Fox
2004; Pampel and Williams 2000; Wadsworth and Roberts 2008; Williams and Flewelling 1987). While we acknowledge the limitations of SHR data, our position
appears to be consistent with other scholars who have used SHR data in their studies
of disaggregated homicide rates (e.g., Dugan et al. 1999; Kovandzic et al. 1998;
Messner and South 1992; Miethe and Drass 1999; Nelsen et al. 1994; Ousey and Lee
2002; Wadsworth and Kubrin 2004; Williams and Flewelling 1987). Specifically, we
believe that the SHR data are an important tool for building better understanding of
the patterns and predictors of variation in the nature of homicide in the US. Indeed,
our view resembles that of Miethe and Regoeczi (2004) who, in their comprehensive
study of homicide situations and circumstances across nearly three decades, noted:
‘‘The SHR data are highlighted as the most comprehensive data on homicide because
of their national scope and inclusion of measures of most of the basic elements that
underlie homicide situations’’ (pg. 13). In sum, SHR data are uniquely useful for the
current study objectives. They provide the only source of detailed information on
homicide incident circumstances across a large sample of cities for the 1980–2010
time period.
Independent Variables
We predict homicide subtypes with key independent variables that occupy a prominent
place in prior studies of crime trends and of disaggregated-homicide rates. To gauge the
effect of immigration, we use two measures, the percent foreign-born and the percent
Latino. Each of these has appeared in prior research investigating the immigration-crime
nexus (e.g., Morenoff and Sampson 1997; Nielsen et al. 2005; Ousey and Kubrin 2009;
Stowell et al. 2009; Wadsworth 2010; Sampson and Morenoff 2004; Sampson et al. 1997).4
In the analyses reported herein, we follow the lead of prior researchers (e.g., Sampson et al.
1997; Stowell et al. 2009) and combine them into an immigration index, computed by
averaging standardized scores for both measures. The overall Pearson’s correlation
between the two items in the index is .704 (within-city correlation = .821, between-city
correlation = .690).
4
A measure of linguistic isolation, the percentage of persons who speak English ‘‘poorly’’ or ‘‘not at all,’’
also has appeared in some studies. We considered using this item in the current analysis. However, because
the linguistic isolation question for the 2010 American Community Survey differs from that of the preceding
Decennial Censuses, we decided against using it.
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463
An extensive body of scholarship, albeit largely cross-sectional, suggests that levels of
homicide in cities (and other geographic units) are associated with variations in socioeconomic disadvantage. To account for the effects of within-city changes in structural
disadvantage, we compute a disadvantage index by averaging the z-scores of four variables: the percent of persons in poverty, the percent of persons aged 16-plus who are
unemployed, the percent of family households headed by a single parent, and the percent of
the city population that identifies as Black/African-American. The Cronbach’s alpha for
this index is .892.5
It is theorized that places with greater family instability experience an attenuation of
adult supervision of youth and a weakened social control capacity, which lead to higher
crime rates, including lethal violence. Moreover, research finds that in general, compared
to the native-born, immigrants have a more familistic and pro-nuptial orientation (Oropesa
and Gorman 2000; Oropesa and Landale 2004). As such, we include a measure of the
percent divorced, which predicts between-city variance in homicide in numerous studies
(Land et al. 1990; McCall et al. 2010; Phillips 2006a). Finally, although longitudinal
research estimating the association between the percent divorced and homicide is more
sparse, there is some supporting evidence (McCall et al. 2008; Ousey and Lee 2002).
Homicide rates also vary as a function of demographic characteristics of cities,
including the overall population size and the relative prevalence of young adults (e.g.,
Levitt 2004; McCall et al. 2008; Ousey 1999; Phillips 2006b). To control for these effects,
our analyses include a measure of the natural logarithm of city population as well as a
measure of the percent of the population comprised of males aged 15–34. Finally, because
there is reason to believe that both immigration and violence may be associated with recent
changes in the labor market structure of cities (Ousey and Kubrin 2009; Parker 2004;
Shihadeh and Ousey 1998), we include a control for the percent employed in professional
or managerial occupations.
For the years between 1980 and 2000, the preceding measures of socioeconomic disadvantage, demographic structure, and occupational composition are computed from
summary files from the decennial census. Measures for 2010 are created from 2010
American Community Survey data (5-year estimates) obtained from the National Historic
Geographic Information System (Minnesota Population Center 2011).
Since scholarship suggests that changes in homicide rates may be linked to fluctuations
in drug market activity and enforcement, as well as changes in policing capacity, we
include two additional predictors in our models. First, we include a measure of the arrest
rate for the sale or distribution of cocaine and opiates obtained from Uniform Crime Report
data (we employ 3-year averaged rates, e.g., 1979–1981 data are used for the 1980 data
point). Second, we compute a measure of the police officer rate (i.e., officers per 1,000
persons) from the Law Enforcement Officers Killed or Assaulted dataset. Finally, to
account for the effects of general temporal trends in the homicide rates measures, we
5
Partly reflecting the influence of the seminal study by Land, McCall, and Cohen (1990), the inclusion of
the percent black in ‘‘disadvantage’’ indices has become common practice. Empirically, this practice is
justified by the high correlations that exist between percent black and other indicators of socioeconomic
disadvantage in geographic units, which is also the case in our data. However, based on conceptual grounds,
some scholars suggest that the percent black should be kept separate from disadvantage index measures. We
believe there is some merit to both of these positions, and while the analyses presented herein employ a
disadvantage index that includes the percent black, we also estimated models in which percent black is
included as a separate predictor. Results from those models are very similar and lead to identical substantive
conclusions as those that we present below.
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include linear and quadratic time trend variables.6 Descriptive statistics for the variables
included in the analysis appear in ‘‘Appendix 2’’.
Analytic Strategy
To model homicide rates, researchers typically employ one of two modeling approaches.
The traditional strategy is to create per capita rates by diving homicide counts by a
relevant population base (e.g., the city population) and then modeling the resulting rate
(or its natural logarithm) via a linear regression estimator. However, studies are
increasingly modeling homicide rates with regression models for counts (e.g., Poisson or
Negative Binomial). The models typically include an ‘‘offset’’ term that effectively
standardizes counts by population size. The movement to the count models is motivated,
in part, by the fact that linear regression can be poorly suited for count-based outcomes,
which are discrete, highly skewed, and non-negative (Osgood 2000). In preliminary
analyses, we estimated our models with both negative binomial and linear regression
estimators and then compared the respective fit of each modeling approach to the
observed data. Overall, the negative binomial models provided a better fit. Hence, our
main presentation and discussion focuses on results obtained from the negative binomial
models.
Since our focus is geared towards explaining within-city changes in homicide, we
employ fixed-effects negative binomial models.7 While fixed-effects models are one of
several modeling strategies for analyzing longitudinal or repeated measures datasets, they
hold the advantage of estimating the effects of measured time-varying predictor variables
while controlling for time-stable omitted variables with time-stable effects (Allison 2005).
In contrast, alternative strategies such as the random-effects model have the disadvantage
of assuming a zero correlation between measured time-varying predictors and time-stable
omitted variables.8
We obtained within-city estimates of the effects of the independent variables by
unconditional maximum likelihood. Specifically, using the negative binomial regression
procedure (‘‘nbreg’’) in Stata version 12, we estimated models that include the predictor
variables described above along with dummy variables for all of the city units except one
(i.e., J - 1 city dummy variables).9 Including the city dummy variables controls for the
effects of city-specific, time-invariant effects, thereby removing all between-city variation
6
The linear time-trend variable is centered at 1990 (i.e., 1990 = 0).
7
To be clear, our analysis approach is distinct from studies that examine cross-sectional effects of structural
covariates at multiple points in time (e.g., Land et al. 1990) as well as from analyses that pool time crosssections together and obtain estimates via ordinary least squares or via random-effects models. Each of the
preceding approaches produces effects that, to varying degrees, reflect between-unit (i.e., between-city)
effects. Our approach removes between-unit variation, focusing only on variation within units over time.
8
If this assumption holds, the random effects model may be preferred due to greater statistical efficiency.
Several tests that compare fixed-effects and random-effects models are available. We use the approach
suggested by Allison (2005), which is based on comparing the coefficients associated with the within-unit
and between-unit components of the same variables. If the assumptions of the random-effects model are
valid, these coefficients should not be significantly different; if they are, the fixed-effects model is preferred.
For each model we estimated, the test procedure supported fixed-effects over the random-effects estimator.
9
Stata software includes a fixed-effects model explicitly designed for panel data analysis, ‘‘xtnbreg, fe.’’
However, Allison and Waterman (2002) showed that the model fails to account for effects of time-stable
omitted variables.
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from our analysis.10 Hence, the coefficients for our explanatory variables reflect the impact
of within-city, over-time variation in those variables on within-city temporal variation in
overall and type-specific homicides.
Our analysis proceeds in four steps. First, we estimate baseline growth models for each
homicide outcome. These models include linear and quadratic measures of time or measurement occasion and give us an image of the patterns of change in each homicide type
from 1980 to 2010. Second, we elaborate the baseline models by incorporating the independent and control variables, including the immigration measure. These models facilitate
an assessment of the effects of within-city change in the explanatory variables on changes
in the various homicide measures. In addition, these models allow us to determine the
extent to which the time trends observed in our initial models are accounted for by changes
in those explanatory variables. Third, we examine models that include an interaction that
estimates whether the effect of within-city changes in immigration vary across cities as a
function of between-city differences in preexisting levels of immigration. Finally,
employing an instrumental variables framework, we conduct supplemental analyses to
assess if there is evidence supporting the notion that immigration is an endogenous predictor of homicide rates. Importantly, these analyses will determine how modeling endogeneity of immigration affects our estimates and thus our substantive conclusions
regarding the impact of within-city changes in immigration on changes in homicide rates.
Results
Overall Homicide Models
In Table 1, we present results from fixed-effects negative binomial regression models
predicting overall homicide rates in 156 US cities. In the first model, we include only the
time trend variables to capture an image of the direction of temporal changes in overall
homicide rates for those cities from 1980 to 2010. Given that the time variables are
centered at 1990, the coefficient for the linear trend conveys the proportional growth rate
for homicide rates measured at the 1990 time point. The coefficient is negative and statistically significant, indicating that homicide rates are declining. The corresponding
quadratic trend is small and positive but not significant, suggesting little evidence of
acceleration or deceleration in the relative rate of change in homicide through the period of
observation.
In the second model of Table 1 we introduce the control variables but leave out the
immigration measure. Six of the predictors have a statistically discernible association with
the relative change in the overall homicide rate. The direction of these effects is generally
consistent with expectations. We find evidence that proportional increases in the overall
10
A caveat is that coefficients in unconditional negative binomial models may be subject to ‘‘incidental
parameters’’ bias (see Allison 2005:95; Allison and Waterman 2002). However, a Monte Carlo simulation
study of this issue suggests the dummy variable approach to fixed-effects negative binomial does not result
in any substantial bias, even under circumstances that are most likely to produce it (see Allison and
Waterman 2002). Nevertheless, according to Allison (2005) one alternative to obtaining fixed-effects
estimates is the ‘‘hybrid model,’’ which decomposes independent variables into time-stable and time-varying
components and includes both in a random-effects regression model. Because the hybrid approach does not
require estimation of dummy variables for each panel unit, it should not be affected by incidental parameters
bias (Allison 2012). Thus, as a supplemental analysis, we also estimated our models via the hybrid method.
Results obtained are nearly identical to those obtained with the unconditional (dummy variable) estimator.
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Table 1 Fixed-effects negative binomial model predicting total homicide in large US cities, 1980–2010
Model 1
Model 2
Model 3
Time trends
Linear
-0.149***
-0.132**
0.00352
Quadratic
0.0151
0.0346*
0.0149
0.0772***
0.0345?
Within-city change variables
Divorced
Disadvantage
0.240***
0.299***
Drug arrest ratea
0.0389**
0.0383**
-0.00855
Police officer rate
-0.0197
Percent males 15–34
0.0678***
0.0773***
City population (Ln)a
-0.228*
-0.0289
Percent professionals
-0.0193***
Immigration
Constant
N 9 T (observations)
-0.0227***
-0.309***
3.344***
1.942**
1.574*
591
591
591
?
p \ 0.1; * p \ .05; ** p \ .01; *** p \ .001. Models include log of the city population as an offset.
Models also include dummy variables for J - 1 cities
a
Coefficients for this variable multiplied by 100 to reduce leading zeros
homicide rate are associated with increases in the percent divorced, socioeconomic disadvantage, the drug arrest rate, and the percent males aged 15–34. In contrast, homicide
rates are negatively associated with within-city changes in the city population and with the
percent employed in professional or managerial occupations. Interestingly, after controlling for these predictors, there is only limited impact on the linear time trend coefficient,
but the quadratic term coefficient increases and becomes statistically significant. This
suggests that some of the deceleration of the homicide growth rate was accounted for by
within-city changes in these measures.
Next we examine the effects of within-city changes in immigration on relative changes
in overall homicides, net of the control variables. Here we find evidence that increases in
immigration have a significant negative association with the overall homicide rate. The
coefficient (-.309) implies that a 10 % increase in the imm...
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