## Description

PSY520

Topic 5 exercises

Complete the following exercises located at the end of each chapter and put them into a Word document to be submitted as directed by the instructor.

Show all relevant work; use the equation editor in Microsoft Word when necessary.

1.Chapter 13, numbers 13.6, 13.8, 13.9, and 13.10

2.Chapter 14, numbers 14.11, 14.12, and 14.14

3.Chapter 15, numbers 15.7, 15.8, 15.10 and 15.14

## Explanation & Answer

Here you go!This was a lot more work than I thought it would be 😧

Topic 5 Exercises

Chapter 13

13.6

It’s well established, we’ll assume, that lab rats require an average of 32 trials in a complex

water maze before reaching a learning criterion of three consecutive error-less trials. To

determine whether a mildly adverse stimulus has any effect on per-formance, a sample of

seven lab rats were given a mild electrical shock just before each trial.

(a) Given that X = 34.89 and s = 3.02, test the null hypothesis with t, using the .05 level of

significance.

Null hypothesis

H0: µ = 32 trials

Alternative hypothesis:

HA: µ ≠ 32 trials

A two-tailed, one sample t-test for the population mean was performed, and yielded the

following test statistic and p-value:

t(df = 6) = 2.53

p = 0.0446

At a significance level of 0.05, the null hypothesis should be rejected (p < ⍺).

Therefore, there is sufficient evidence to conclude that the true number of trials required to learn

the water maze is a value other than 32.

(b) Construct a 95 percent confidence interval for the true number of trials required to

learn the water maze.

Sample Mean ± Margin of Error

34.89 ± 2.447*(1.14)

(32.097, 37.683)

(c) Interpret this confidence interval.

We are 95% confident that the true population number of trials required to learn the water maze

falls between 32.1 and 37.7.

13.8

Assume that, on average, healthy young adults dream 90 minutes each night, as inferred

from a number of measures, including rapid eye movement (REM) sleep. An investigator

wishes to determine whether drinking coffee just before going to sleep affects the amount of

dream time. After drinking a standard amount of coffee, dream time is monitored for each

of 28 healthy young adults in a random sample. Results show a sample mean, X, of 88

minutes and a sample standard deviation, s, of 9 minutes.

(a) Use t to test the null hypothesis at the .05 level of significance

Null hypothesis

H0: µ = 90 minutes of dreaming a night

Alternative hypothesis:

HA: µ ≠ 90 minutes of dreaming a night

A two-tailed, one sample t-test for the population mean was performed, and yielded the

following test statistic and p-value:

t(df=27) = -1.18

p = 0.2499

At a significance level of 0.05, the null hypothesis should not be rejected (p > ⍺).

Therefore, there is not sufficient evidence to conclude that the true length of time that a healthy,

young adult dreams each night is any value other than 90 minutes.

(b) If appropriate (because the null hypothesis has been rejected), construct a 95 percent

confidence interval and interpret this interval.

As the decision that was made was to fail to reject the null hypothesis, there is no need to

construct a confidence interval. If an interval were constructed, it would contain the null

hypothesis value of 90 minutes.

13.9

In the gas mileage test described in this chapter, would you prefer a smaller or a larger

sample size if you were:

(a) the car manufacturer? Why?

A smaller sample size would be preferable.

As the sample size decreases, the width of the confidence interval increases, which is ideal for

the car manufacturer.

(b) a vigorous prosecutor for the federal regulatory agency? Why?

A larger sample size would be preferable.

As the sample size increases, the width of the confidence interval decreases, which makes the

estimate more precise. This is beneficial for the federal agency because more prosecutions would

occur.

13.10 Even though the population standard deviation is unknown, an investigator uses z rather

than the more appropriate t to test a hypothesis at the .05 level of significance.

(a) Is the true level of significance larger or smaller than .05?

Larger.

(b) Is the true critical value larger or smaller than that for the critical z?

Larger.

Chapter 14

14.11 To test compliance with authority, a classical experiment in social psychology requires

subjects to administer increasingly painful electric shocks to seemingly helpless victims

who agonize in an adjacent room. Each subject earns a score between 0 and 30, depending

on the point at which the subject refuses to comply with authority—an investigator,

dressed in a white lab coat, who orders the administration of increasingly intense shocks. A

score of 0 signifies the subject’s unwillingness to comply at the very outset, and a score of

30 signifies the subject’s willingness to comply completely with the experimenter’s orders.

Ignore the ...