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# chapter_23 - CHAPTER 23 SOLUTIONS AND MINI-PROJECT NOTES...

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CHAPTER 23 SOLUTIONS AND MINI-PROJECT NOTES CHAPTER 23 HYPOTHESIS TESTING—EXAMPLES AND CASE STUDIES EXERCISE SOLUTIONS 23.1 a. Null : It is not the case that a majority of American Catholics favor allowing women to be priests. Alternative : A majority of American Catholics favor allowing women to be priests. b. Standard deviation is the square root of (0.5)(0.5)/507 = 0.022; standardized score is (0.59 - 0.50)/0.022 = 4.05. c. Reject the null hypothesis. We can conclude that a majority of American Catholics favor allowing women to be priests. 23.2 One-sided, because the alternative includes values above 0.50 only. 23.3 Double the value to get 0.06. 23.4 a. No, because 0.08 > 0.05. b. Yes, the p-value would be 0.04. 23.5 Use z -score = (sample mean - hypothesized mean)/SEM; find SEM using the standard deviation divided by the square root of the sample size. 23.6 a. 2 × 0.015 = .03 b. 0.023 c. 2.16 × 10 -5 = 0.0000216 23.7 a. Null : The training program has no effect on test scores. Alternative : Test scores will be higher after the training program. b. Standardized score = (10 - 0)/4 = 2.5. c. From Table 8.1, the p-value is between 0.01 and 0.005, so reject the null hypothesis and conclude that scores would be higher after the program. d. The students had already taken the test once, before the program, so when they took it afterward they were familiar with the test already. e. Randomly assign some students to take the program and others to not take it, using matched pairs if possible. Compare scores after the program. 23.8 A type 1 error would be that there is no relationship but that the study found one, in which case the law discriminating by ages would have been upheld. A type 2 error would be that there is a relationship but it was not detected, in which case the law was not upheld, but perhaps should have been because young males are more likely to drink and drive than young females. 23.9 The null hypothesis was that mental scores are not changed by taking estrogen, while the alternative is that they are. (It is not clear if the alternative was one-sided, saying scores increase.) The study found that the null hypothesis could be rejected, so the p-value must have been 0.05 or less. 23.10 a. Null : In the population of elderly people, there is no relationship between pet ownership and number of doctor contacts. Alternative : In the population of elderly people, those with pets have fewer doctor contacts than those without pets. b. Because we are told that the p-value is less than 0.05, we can reject the null hypothesis. We can conclude that elderly people with pets have significantly fewer doctor contacts than those without pets. 23.11

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## This note was uploaded on 10/15/2011 for the course STAT 100 at Penn State.

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chapter_23 - CHAPTER 23 SOLUTIONS AND MINI-PROJECT NOTES...

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