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

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 errorless trials. To determine whether a mildly adverse stimulus has any effect on performance, a sample of seven lab rats were given a mild electrical shock just before each trial.

(a) Given that \(\bar{X}=\) 34.89 and s = 3.02, test the null hypothesis with t, using the .05 level of signifi cance.

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

(c) Interpret this confidence interval.

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 sampl e. Results show a sample mean, \(\bar{X} \) , 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 .

(b) If appropriate (because the null hypothesis has been rejecte d), construct a 95 percent confi dence interval and interpret this interval.

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?

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

13.10 Even though the population standard deviation is unknown, an investigator uses z rather than the more appropriate t to test a hypoth esis at the .05 level of significance .

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

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

14.11 To test compliance with authority, a classic al experiment in social psychology requires subjects to administer increasingly painful electric shocks to seemingly helpless victims who agonize in an adjacent room.* Each sub ject 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 inte nse shocks. A score of 0 signi fi es the subject’s unwillingness to comply at the very o utset, and a score of 30 signi fi es the subject’s willingness to comply completely with the experimenter’s orders.

Ignore the very real ethical issues raised by this type of experiment, and assume that you want to study the effect of a "committee atmosphere" on compliance with authority. In one condition, shocks are administered only after an affi rmative decision by the committee, consisting of one real subject and two associates of the investigator, who act as subjects but in fact merely go along with the decision of the real subject. In the other condition, shocks are administered only after an af fi rmative decision by a solitary real subject. A total of 12 subjects are randomly assigned, in equal numbers, to the committee condition ( X 1 ) and to the solitary condition ( X 2 ). A compliance score is obtained for each subject. Use t to test the null hypoth esis at the .05 level of significance .

COMPLANCE SCORES

COMMITTEE SOLITARY

2 3

5 8

20 7

15 10

4 14

10 0

14.12 To determine whether training in a series of workshops on creative think ing increases IQ scores, a total of 70 students are randomly divided into treatment and control groups of 35 each. After two months of training, the sample mean IQ ( –X1) for the treatment group equals 110, and the sample mean IQ ( –X2) for the control group equals 108. The estimated standard error equals 1.80.

(a) Using t , test the null hypoth esis at the .01 level of significance .

(b) If appropriate (because the null hypothesis has been rejected), estimate the standardized effect s ize, construct a 99 percent conf i dence interval for the true population mean difference, and interpret these estimates.

*14.14 An investigator wishes to determine whether alcohol consumption causes a deterioration in the performance of automobile drivers. Before the driving test, subjects drink a glass of orange juice, which, in the case of the treatment group, is laced with two ounces of vodka. Performance is measured by the number of errors made on a driving simulator. A total of 120 volunteer subjects are randomly assigned, in equal numbers, to the two groups. For subjects in the treatment group, the mean number of errors ( –X1) equals 26.4, and for subjects in the control group, the mean number of errors ( –X2) equals 18.6. The estimated standard error equals 2.4.

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

(b) Specify the p -value for this test result.

(c) If appropria te, construct a 95 percent confidence interval for the true population mean difference and interpret this interval.

(d) If the test result is statistically signi fi cant, use Cohen’s d to estimate the effect size, given that the standard deviation, sp , equals 13.15.

(e) State how these test results might be reported in the literature, given s =1 5 13.99 and s2= 2 5 12.15.

*15.7 An educational psychologist wants to check the claim that regular physical exercise improves academic achievement. To control for academic aptitude, pairs of college students with similar GPAs are randomly assigned to either a treatment group that attends daily exercise classes or a control group. At the end of the experiment, the following GPAs are reported for the seven pairs of participants:

Pair Number Physical Exercise (X1) No Physical Exercise (X2)

1 4.00 3.75

2 2.67 2.74

3 3.65 3.42

4 2.11 1.67

5 3.21 3.00

6 3.60 3.25

7 2.80 2.65

(a) Using t , test the null hypoth esis at the .01 level of significance .

(b) Specify the p -value for this test result.

(c) If appropriate (because the test result is statistically signi fi cant), use Cohen’s d to estimate the effect size.

(d) How might this test result be reported in the literature?

15.8 A school psychologist wishes to determine whether a new antismoking fi lm actually reduces the daily consumption of cigarettes by teenage smokers. The mean daily cigarette consumption is calculated for each of eight teen-age smokers during the month before and the month after the fi lm presen tation, with the following results:

MEAN DAILY CIGARETTE CONSUMPTION

SMOKER NUMBER BEFORE FILM (X1) AFTER FILM (X2)

1 28 26

2 29 27

3 31 32

4 44 44

5 35 35

6 20 16

7 50 47

8 25 23

t TEST FOR TWO RELATED SAMPLES (REPEATED MEASURES)

(Note: When deciding on the form of the alternative hypothesis, H 1, remember that a positive difference score (D = X1- X2) re fl ects a decline in cigarette consumption.)

(a) Using t, test the null hypothesis at the .05 level of significance .

(b) Specify the p -value for this test result.

(c) If appropriate (because the null hypothesis was rejected), construct a 95 percent confidence interval for the true population mean for all difference scores, and use Cohen’s d to obtain a standardized estimate of the effect size. Interpret these results.

(d) What might be done to improve the design of this experiment?

Price: $31.8

Solution: The downloadable solution consists of 10 pages, 2180 words.
Deliverable: Word Document