Exam 6: Comparing Two Proportions

A Gallup poll headline from April 25, 2013, reads "In U.S., Women Veterans Rate Lives Better Than Men". In a random sample of 900 female veterans interviewed, 459 rated their lives as "thriving." Only 693 male veterans rated their lives as "thriving" in a random sample of size 1,650. What is the null hypothesis if researchers are interested in determining if the long-run proportion who would rate their lives as thriving differs between women and men?

A 2003 study reported in the Journal of Consumer Affairs examined how well consumers protect themselves from identity theft. The study surveyed a random sample of 61 college students and 59 non-students, and asked each participant, "Have you used personal information (such as birth date, pet name, etc.) when creating a password?" For the students, 22 agreed with this statement, while 30 of the non-students agreed. -If we increased the confidence level from 95% to 99%, all else remaining the same, the center of the confidence interval would

The Women's Health Study included 39,876 female health professionals aged 45 years and older who were followed for an average of 10 years (Ridker et al., 2005). At the beginning of the study, participants were randomly assigned to take either a daily low-dose aspirin or a daily placebo pill for the duration of the study. At the end of the study, researchers measured the number of participants that suffered from a heart attack during the study. Data are summarized in the following table. -Does there appear to be an association between whether a woman takes low-dose Aspirin or placebo and if she suffers from a heart attack in this sample?

The Women's Health Study included 39,876 female health professionals aged 45 years and older who were followed for an average of 10 years (Ridker et al., 2005). At the beginning of the study, participants were randomly assigned to take either a daily low-dose aspirin or a daily placebo pill for the duration of the study. At the end of the study, researchers measured the number of participants that suffered from a heart attack during the study. Data are summarized in the following table. -What type of plot could be used to plot these data?

To investigate biases against women in personnel decisions, psychologists performed a randomized experiment on 50 male bank supervisors attending a management institute who volunteered for the study. The supervisors were asked to make a decision on whether to promote a hypothetical applicant based on a personnel file. For 26 of them, the application file described a female candidate; for the others it described a male. The files were identical in all other respects. Results on the promotion decisions for the two groups are shown below. -The p-value for this study is 0.009. How would you interpret this value?

A Gallup poll headline from April 25, 2013, reads "In U.S., Women Veterans Rate Lives Better Than Men". In a random sample of 900 female veterans interviewed, 459 rated their lives as "thriving." Only 693 male veterans rated their lives as "thriving" in a random sample of size 1,650. -The relative risk of a "thriving" life rating for female veterans compared to male veterans is 1.214. How would you interpret this value?