Eleven male subjects responded to an attitude questionnaire designed to evaluate their tendency to view women in stereotypic roles. A month later they were shown a film that illustrated the ways in which women have often been treated unfairly relative to men. Four months later the subjects again responded to the attitude questionnaire. The subjects' scores on the questionnaire (the higher the score, the greater the bias) before and after were as follows:
Subject: A B C D E F G H I J K
Before: 21 25 31 26 21 31 28 24 27 24 22
After: 13 26 35 24 17 24 22 27 17 19 18
(a) Conduct a non directional test for a difference in response between the two sets of data. Use the Wilcoxon signed-ranks test and the 5% significance level.
(b) Calculate effect size.
(c) Do you feel that the way the study was conducted was adequate? Explain. 14. Rework Problem 13a using the large sample (z) Wilcoxon approach.