15.5: Chapter Exercises
- Page ID
- 95152
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Chapter Exercises
- There are people who think that there is a strong positive correlation between having the astrological sign Libra and being indecisive. Why might they have come to think this? What claim does this make about correlations? How would you go about assessing this claim?
- The following passages are from a column in The Oklahoma Daily (April 13, 1998) in which Rep. Bill Graves argues that people who are gay should not be employed as support personnel at public schools. For each of the following, (1) explain Graves’ point in citing the statistics, and (2) critically evaluate his use of the statistics.
- “The 1948 Kinsey survey . . . found that 37 percent of homosexual men and 2 percent of lesbians admitted sexual relations with children under 17 years old. Twenty-eight percent of homosexual men and 1 percent of lesbians admitted sexual relations with children under 16 years old while they were age 18 or older.”
- “The average age of homosexual men is 39 years, and 45 years for lesbians. Thus, that lifestyle is actually a death style from which children should be protected.”
- Evaluate the following interchange:
Wilma: I’ve just graduate from law school and now I must take the bar exam. I’m sort of nervous about passing.
Wilbur: Don’t about 90% of those who take it pass?
Wilma: It’s given twice a year. In the summer about 90% pass it; in the winter, it’s about 70%.
Wilbur: I’d take it in the summer if I were you.
- Political consultants increasingly use focus groups to determine which themes, even which words, their candidate should use to get more votes. What is a focus group and how do they work (check the internet if you aren’t sure)? Then explain the ways in which the concepts introduced in this chapter, e.g., sample and population, bear on the use of such groups and the evaluation of their responses.
- Personnel Director for a large company: We are very careful in our job interviews. We see some very good people, and the decisions are often tough. But looking back, we have almost always made the best decisions. The people we have hired have worked out very well.
- When a teacher gives you an examination, they are taking a sample of the things you have learned in the course. Explain, in more detail, what the sample and the population are in this case. What does it mean for a sample to be biased in this case? In what ways are good tests unbiased?
- Answers to Selected Exercises
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- There is a problem with this sample. To see whether the hiring decisions were the best, the Personnel Director would need to know how the people she didn’t hired would have worked out. This is nearly impossible to know, but failing this, it would be useful to know how the people who weren’t hired ending up doing at the job they eventually got.