before attempting to solve Formula 9.2. Also, in Formula 9.4, perform the mathematical operations in the proper sequence. First square each sample standard deviation, then divide by the proper N, add the resultant values, and then find the square root of the sum.)

a.

c.

GLOSSARY Independent random samples. Random samples gathered in such a way that the selection of a particular case for one sample has no effect on the probability that any other particular case will be selected for the other samples.

Pooled estimate. An estimate of the standard deviation of the sampling distribution of the difference in sample means based on the standard deviations of both samples.

sp p. Symbol for the standard deviation of the sampling distribution of the differences in sample proportions.

s . Symbol for the standard deviation of the sampling distribution of the differences in sample means.

X X Sample 1 Sample 2 72.5 76.0 s 14.3 s2 10.2 N1 136 N2 257 X2 X1 Sample 1 Sample 2 107 103 s1 14 s2 17 N1 175 N2 200 X2 X1

b. 9.2 Gessner and Healey administered questionnaires to samples of undergraduates. Among other things, the questionnaires contained a scale that measured attitudes toward interpersonal violence

(higher scores indicate greater approval of interpersonal violence). Test the results as reported here for sexual, racial, and social-class differences.

a.

SOC Sample 1 Sample 2

(Males) (Females 2.99 2.29 s1 0.88 s2 0.91 N1 122 N2 251 X2 X1

b. Sample 1 Sample 2

(Blacks) (Whites) 2.76 2.49 s1 0.68 s2 0.91 N1 43 N2 304 X2 X1 Sample 1 Sample 2

(White Collar) (Blue Collar) 2.46 2.67 s1 0.91 s2 0.87 N1 249 N2 97 X2 X1

d. Summarize your results in terms of the significance and the direction of the differences. Which of these three factors seems to make the biggest difference in attitudes toward interpersonal violence?