504 CHAPTER 9 Inferences from Two Samples 1. Out-of-class activity Exercise 7 in Section 9-1 included data from a MythBusters episode involving a drop test of buttered toast and toast that was marked with an X on one side (but not buttered). Construct your own experiment to replicate the one televised on MythBusters. What do you conclude about the results? 2.Out-of-class activity Working in groups of three or four students, each group should make observations and collect data to determine whether there is a cost difference between genders for a particular product or service, such as prices of haircuts or the cost of dry cleaning men’s and women’s pants or shirts. 3.Out-of-class activity Pedometers are used to count the number of steps that a person walks. Those steps are often converted to distances, often by calibrating the pedometer. High school and college running tracks are typically either 400 meters in length or 440 yards in length. Use such a track with a known length and conduct an experiment to test the accuracy of a pedometer. Some pedometers are inexpensive, such as less than $1. Others, such as a Fitbit, are much more expensive. Also, there are free smartphone apps that can function as pedometers. 4.Out-of-class activity Exercise 17 in Section 9-1 is based on observations of cars with only rear license plates in states with laws that require both front and rear license plates. Work together in groups of three or four and collect data in your state. Use a hypothesis test to test the claim that in your state, the proportion of cars with only rear license plates is the same as the proportion of 239>2049 from Connecticut. (Connecticut students can compare the proportion they get to the proportion of 239>2049 obtained by the author.) 5.Out-of-class activity Survey couples and record the number of credit cards each person has. Analyze the paired data to determine whether the males in couple relationships have more credit cards than the females. Try to identify reasons for any discrepancy. 6.Out-of-class activity Measure and record the height of the male and the height of the female from each of several different couples. Estimate the mean of the differences. Compare the result to the difference between the mean height of men and the mean height of women included in Data Set 1 “Body Data” in Appendix B. Do the results suggest that height is a factor when people select couple partners? 7. Out-of-class activity Are estimates influenced by anchoring numbers? Refer to the related Chapter 3 Cooperative Group Activity on page 140. In Chapter 3 we noted that, according to author John Rubin, when people must estimate a value, their estimate is often “anchored” to (or influenced by) a preceding number. In that Chapter 3 activity, some subjects were asked to quickly estimate the value of 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1, and others were asked to quickly estimate the value of 1 * 2 * 3 * 4 * 5 * 6 * 7 * 8. In Chapter 3, we could compare the two sets of results by using statistics (such as the mean) and graphs (such as boxplots). The methods of this chapter now allow us to compare the results with a formal hypothesis test. Specifically, collect your own sample data and test the claim that when we begin with larger numbers (as in 8 * 7 * 6), our estimates tend to be larger. 8.In-class activity Divide into groups according to gender, with about 10 or 12 students in each group. Each group member should record his or her pulse rate by counting the number of heartbeats in 1 minute, then the group statistics 1n, x, s2 should be calculated. The groups should test the null hypothesis of no difference between their mean pulse rate and the mean of the pulse rates for the population from which subjects of the same gender were selected for Data Set 1 “Body Data” in Appendix B. Cooperative Group Activities
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