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.
-If we had calculated a 95% confidence interval in question 33 rather than a 90% confidence interval, all else being equal, would the resulting interval be wider, narrower, or the same width?

Question

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. 
-If we had calculated a 95% confidence interval in question 33 rather than a 90% confidence interval, all else being equal, would the resulting interval be wider, narrower, or the same width?

Quizplus · Accepted Answer

A 95% confidence interval is wider than a 90% confidence interval because it reflects a higher level of certainty, requiring a larger range to capture the true parameter with the increased confidence level.

The Women's Health Study Included 39,876 Female Health Professionals Aged