91Ó°ÊÓ

You visit the online Harris Interactive Poll. Based on 2223 responses, the poll reports that \(60 \%\) of U.S. adults believe that chef is a prestigious occupation. - You should refuse to calculate a \(95 \%\) confidence interval for the proportion of all U.S. adults who believe chef is a prestigious occupation based on this sample because a. this percentage is too small. b. inference from a voluntary response sample can't be trusted. c. the sample is too large.

Divorces. Divorce rates vary from city to city in the United States. We have lots of data on many U.S. cities. Statistical software makes it easy to perform dozens of significance tests on dozens of variables to see which ones best predict divorce. One interesting finding is that those cities with Major League ballparks tend to have significantly more divorces than other cities. To improve your chances of a lasting marriage, should you use this "significant" variable to decide where to live? Explain your answer.

Error Probabilities. You read that a statistical test at significance level \(\alpha=0.05\) has power \(0.80\). What are the probabilities of Type I and Type Il errors for this test?