Bulimia study. The “fear of negative evaluation” (FNE) scores for 11 female students known...

Bulimia study. The “fear of negative evaluation” (FNE) scores for 11 female students known to suffer from the eating disorder bulimia and 14 female students with normal eating habits, first presented in Exercise Research on eating disorders. Data from a psychology experiment were reported and analyzed in The American Statistician (May 2001). Two samples of female students participated in the experiment. One sample consisted of 11 students known to suffer from the eating disorder bulimia; the other sample consisted of 14 students with normal eating habits. Each student completed a questionnaire from which a “fear of negative evaluation” (FNE) score was produced. (The higher the score, the greater was the fear of negative evaluation.) The data are saved in the BULIMIA file and displayed in the following table: are reproduced in the next table and saved in the BULIMIA file. (Recall that the higher the score, the greater is the fear of a negative evaluation.) Based on Randles, R. H. “On neutral responses (zeros) in the sign test and ties in the Wilcoxon–Mann–Whitney test.” The American Statistician, Vol. 55, No. 2, May 2001

a. Construct a dot plot or stem-and-leaf display for the FNE scores of all 25 female students.

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b. Highlight the bulimic students on the graph you made in part a. Does it appear that bulimics tend to have a greater fear of negative evaluation? Explain.

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c. Why is it important to attach a measure of reliability to the inference made in part b ?

a. Locate a 95% confidence interval for the difference between the population means of the FNE scores for bulimic and normal female students on the MINITAB printout shown at the bottom of page 365. Interpret the result.

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b. What assumptions are required for the interval of part a to be statistically valid? Are these assumptions reasonably satisfied? Explain.