Practical Research: Planning and Design
Twelfth Edition
Chapter 6
Descriptive Research
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Descriptive Research Designs
• Observation studies
• Correlational research
• Developmental design
• Survey research
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Quantitative Observation Studies
• Involve humans, other animals, plants, nonliving objects
• Focus is limited, pre-specified
• Quantify behavior
• Require planning, attention to detail, and time
• Provide a quantitative alternative to qualitative
approaches
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Maintaining Objectivity in Observation
Studies (1 of 2)
• Define the behavior precisely and concretely
– Should be easily recognized
• Divide the observation period into small segments
– Record whether the behavior does or does not occur
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Maintaining Objectivity in Observation
Studies (2 of 2)
• Use a rating scale to evaluate the behavior in terms of
specific dimensions
– Have people rate the same behavior independently
• Train the raters to use specific criteria until consistent
ratings are obtained
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Correlational Research (1 of 2)
• Examines the extent to which differences in one variable
are related to differences in other variables
• Researchers gather data about two or more
characteristics for a particular group to see if these
characteristics are interrelated
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Correlational Research (2 of 2)
• Scatter plots show the overall pattern and describe the
interrelationship
• Correlation does not, in and of itself, indicate causation
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Developmental Designs
• Cross-sectional study
– people from several different groups are sampled and
compared
• Longitudinal study
– a single group of people is followed over time, and
data are collected at various times
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Pros and Cons: Cross-Sectional V s.
Longitudinal Study (1 of 2)
ersu
• Cross-sectional studies:
– Pro
▪ All the data can be collected at one time
– Con
▪ Different populations may represent different life
experiences (threat to internal validity)
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Pros and Cons: Cross-Sectional V s.
Longitudinal Study (2 of 2)
ersu
• Longitudinal studies:
– Pro
▪ Correlations between characteristics at different
times can be computed
– Con
▪ Participants may be lost to follow-up
▪ Characteristic being measured may change
because participants have experience with the
instrument
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Compromise: Cohort-Sequential Design
• Addresses weaknesses of longitudinal and crosssectional designs
• Includes two or more age groups (the cross-sectional
piece), followed over a period of time (the longitudinal
piece)
• Allows calculation of correlations between measures
taken at two different time periods
• Predictions can be made across time
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Experience-Sampling Methods (ESM)
• An experience-sampling method (ESM) is an approach in which a
researcher collects frequent and ongoing data about people as they
live their normal, everyday lives
• Successfully used in both quantitative and qualitative projects
• Advantages of ESM methods:
– Potential for increased accuracy and validity of assessments
– Researcher gains data that might be useful in determining testretest reliability.
– Useful if the researcher wants to collect longitudinal data as a
means of investigating any short-term changes in characteristic
as environmental or behavioral variables change
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Survey Research
• Goal is to learn about a large population by surveying a
sample of that population
• Also called a descriptive survey or normative survey
• Simple design – researcher poses a series of questions,
quantifies responses, and draws inferences about a
population
• Captures a fleeting moment of time — extrapolation can
be made about a longer period of time
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Types of Survey Research
• Interview
– Structured or semi-structured
– Face-to-face, telephone, video conference
– High response rate
• Questionnaire
– Paper-and-pencil or computerized
– Low return rate
– Assurance of remaining anonymous
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Data Collection (1 of 2)
• Checklist: a list of behaviors, characteristics, or other
entities under investigation
• Limited information: observed or not observed
• Rating scale: used to evaluate a behavior, attitude etc. on
a continuum (“never” to “always”)
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Data Collection (2 of 2)
• May be ordinal or interval scale
– People may not interpret scale the same way
• Rubric: two or more rating scales, with concrete
descriptions of behavior for each scale point
– Scales may not address the same things
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Computerizing Observations
• Use a computer to record what you see
• Use a spreadsheet to organize the data
• Consider software specific to your purpose
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Conducting Interviews in a Quantitative
Study (1 of 2)
1. Ask questions that help answer the research question
2. Write questions with quantifiable answers (numerical
codes)
3. Restrict questions to a single idea
4. Consider asking a few questions to elicit qualitative data
5. Use a computer to streamline the process
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Conducting Interviews in a Quantitative
Study (2 of 2)
6. Conduct pilot test(s)
7. Introduce yourself and explain the purpose of the study
8. Be sure participants offer informed consent in writing
9. Ask controversial questions in the latter part of the
interview
10.Seek clarifying information as needed
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Constructing a Questionnaire (1 of 3)
1. Keep it short
2. Keep the respondent’s task simple
3. Provide specific instructions
4. Use simple, clear, unambiguous language
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Constructing a Questionnaire (2 of 3)
5. Give a rationale for any item for which the purpose is
unclear
6. Check for unwarranted assumptions implicit in the
question
7. Word your questions in ways that don’t give clues about
preferred or more desirable responses
8. Determine in advance how you will code the responses
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Constructing a Questionnaire (3 of 3)
9. Check for consistency
10.Conduct one or more pilot tests to determine the validity
of your questionnaire
11.Scrutinize the almost-final product to make sure it
addresses your needs
12.Make the questionnaire attractive and professional
looking
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Using Technology When Administering
Questionnaires
1. Ask participants in the same location to answer directly
on a laptop or tablet
2. When participants are at diverse locations, use email to
request participation and obtain responses
3. If you use paper mail delivery, us a word-processing
program to personalize your correspondence
4. Use a scanner to facilitate data tabulation
5. Use a computer database to keep track of who has
responded and who has not
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Maximizing the Return Rate (1 of 2)
1. Consider the timing
– Avoid holidays and vacation times
2. Make a good first impression
3. Motivate potential respondents
– Write a great cover letter
– Include a self-addressed envelope with prepaid
postage
– Offer to send the results of your study
4. If mailing your questionnaire, include a self-addressed
envelope with return package.
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Maximizing the Return Rate (2 of 2)
5. Offer the results of your study
6. Be gently persistent
– Consider sending two follow-up reminders
– Send reminders a week or two after the previous
mailing
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Choosing a Sample in a Descriptive Study
• Any researcher who conducts a descriptive study wants
to determine the nature of how things are…
• It isn’t possible to survey an entire population of interest,
so researchers select a subset, or sample, of the
population.
• A good sample is representative of the population.
• This is what quantitative researchers refer to as external
validity, of the extent to which the study’s findings can be
reasonably generalized beyond the partcipants in the
study.
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Probability Sampling
• Probability sampling: researcher specifies in advance that
each segment of the population is represented in the
sample
– Requires random selection
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Random Selection
• Each member of the population has an equal chance of
being selected
• Characteristics of the sample are assumed to
approximate the characteristics of the total population
• Tables of random numbers or computer programs are
used to select from a list of the population
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Probability Sampling Techniques (1 of 4)
• Simple random sampling: Researcher numbers everyone
in the population and then uses random number
generator to select participants
• Stratified random sampling: Researcher identifies strata
— different groups in population — and samples equally
from each one
– Example: 10 students in each grade
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Probability Sampling Techniques (2 of 4)
• Proportional stratified sampling: Researcher identifies
strata and samples from each one based on its
proportion in the population
– Example:
▪ population: 100 first graders, 200 second graders
▪ sample: 10 first graders, 20 second graders
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Probability Sampling Techniques (3 of 4)
• Cluster sampling: Researcher subdivides a large area
into smaller units (clusters), selects a subset of clusters,
and then selects individuals randomly from each
identified cluster
• Example:
– Population = all students in a district with 1200
schools
– Clusters = townships within the district
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Probability Sampling Techniques (4 of 4)
• Systematic sampling: researcher selects
individuals/clusters according to predetermined
sequence, which must originate by chance
• Example:
– Scramble the list of people randomly
– Then pick every nth person
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Nonprobability Sampling
• Nonprobability sampling: researcher cannot guarantee
that each element of the population will be represented in
the sample
– Some members of the population have little or no
chance of being sampled
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Nonprobability Sampling Techniques (1 of 3)
• Convenience sampling (accidental sampling)
– Researcher takes samples that are readily available.
▪ Example: People who arrive at the store for
breakfast
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Nonprobability Sampling Techniques (2 of 3)
• Quota sampling:
– Researcher conveniently selects participants in the
same proportion that they are found in the general
population, but not in a random fashion
▪ Example population: 100 first graders, 200 second
graders
▪ Example sample: the first 10 first graders and the
first 20 second graders who arrive at school that
day
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Nonprobability Sampling Techniques (3 of 3)
• Purposive sampling: Researcher choose participants for
a particular purpose
– People from voting districts that, in the past, have
been helpful in predicting the election outcome
– The researcher must always provide a rationale
explaining the selection of a particular sample
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Surveys of Very Large Populations (1 of 2)
• Multistage sampling:
– Divide country into primary areas, randomly select
areas to sample
– Divide the primary areas into sample locations,
randomly select locations to sample
– Divide sample locations into chunks, randomly select
chunks to sample
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Surveys of Very Large Populations (2 of 2)
• Multistage sampling:
– Divide chunks into segments, randomly select
segments to sample
– Divide segments into units, randomly select units to
sample
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Identifying a Sufficient Sample Size (1 of 2)
• Basic rule: The larger the sample, the better
• For smaller populations (N=100 or fewer), survey the
entire population
• If population is around 500, sample 50%
• If population is around 1,500, sample 20%
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Identifying a Sufficient Sample Size (2 of 2)
• If population is over 5,000, a sample size of 400 is fine
• The larger the population, the smaller the percentage
• Need a representative sample
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Sources of Bias (1 of 4)
• Bias
– any influence, condition, or set of conditions that
distort the data
• Researchers should try to avoid bias, but acknowledge
that it occurs
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Sources of Bias (2 of 4)
• Sampling Bias
– occurs when any factor(s) leads to a nonrepresentative sample of the population
• Examples:
– Selecting from phone book (no land line?)
– Using an online survey (no Internet?)
– Mailing questionnaires (low or selective response
rate?)
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Strategies for Identifying Sampling Bias
• Look for items that may be influenced by factors that
distinguish respondents from nonrespondents.
– interests, education level, age, etc.
• Compare responses that were returned quickly with those
that were returned later.
– late responses often look like what you’d expect from
nonrespondents
• Randomly select a small number of nonrespondents and
try to contact them.
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Sources of Bias (3 of 4)
• Instrumentation bias
– measurement instruments slant the results
– questions lead to particular answers
• Response bias
– participants say what they think researcher wants to
hear
– participants want to create favorable impression
(social desirability effect)
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Sources of Bias (4 of 4)
• Researcher bias
– researchers have a point of view
– researchers choose what they want to study
– researchers make subjective interpretations
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Interpreting the Data
• Don’t forget — it’s “descriptive” research, but you still
have to interpret the data
• Two basic principles of research:
1. The purpose of research is to seek the answer to a
problem or question in light of data that relate to the
problem or question.
2. Although collecting data for study and organizing it for
inspection require care and precision, extracting
meaning from the data is paramount and should never
be neglected.
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Questions to Ask Yourself (1 of 2)
1. Why is a description of this population and/or
phenomenon valuable?
2. What specific data will you need to address your
research problem and its subproblems?
3. What procedures should you use to obtain the needed
information? How can you best implement those
procedures?
4. How can you get a sample that will reasonably
represent the overall population about which you are
concerned?
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Questions to Ask Yourself (2 of 2)
5. How can you control for possible bias in your collection
of data?
6. What will you do with the data once you have collected
them? How might you best organize and prepare them
for analysis?
7. Above all, in what ways might you reasonably interpret
your data? What conclusions might you reach from your
investigation?
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Copyright
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Homework 6: Descriptive Research Instructions
Q1. The authors of your textbook suggest that sampling bias is virtually unavoidable and
that it is important to disclose and discuss possible sources of bias in the study report.
Do you agree? Explain your position. What are the types of bias? Give examples related
to IA discipline (cybersecurity related examples).
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