solution_to_chapter_12_13_and_14_problems - Solution to...

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Solution to homework 4 problems Problems assigned from chapter 12 2, 8, 9, 34, 36 Problems solved in lecture 7, 20, 22, 23, 35 SOLUTIONS 2. Student Center Survey. a) The students are not using a simple random sample. The samples are designed to get 50 students from each grade level. This would be very unlikely to happen in a simple random sample. b) They are using a stratified sample, with four strata, one for each class year. 7. Population – human resources directors of Fortune 500 companies Parameter – proportion of directors who don’t feel that surveys intruded on their workday Sampling Frame – list of HR directors at Fortune 500 companies Sample – the 23% of the HR directors who responded Method – questionnaire mailed to all (non-random) Bias – nonresponse. It is impossible to generalize about the opinions all HR directors because the nonrespondents would likely have a different opinion about the question. HR directors who feel that surveys intrude on their workday would be less likely to respond. 194 Part III Gathering Data 8. Population – all U.S. adults Parameter – proportion that feels marijuana should be legalized for medicinal purposes Sampling Frame – none given –potentially all people with access to web site Sample – those visiting the web site who responded Method – voluntary response (no randomization employed) Bias – voluntary response sample. Those who visit the website and respond may be predisposed to a particular answer. 9. Population – all U.S. adults Parameter – proportion who have used and benefited from alternative medical treatments. Sampling Frame – all Consumers Union subscribers Sample – those subscribers who responded Method – not specified, but probably a questionnaire mailed to all subscribers Bias – nonresponse bias, specifically voluntary response bias. Those who respond may have strong feelings one way or another. 20. Parent opinion, part 2. a) This sampling method suffers from voluntary response bias. Only those who see the show and feel strongly will call.
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b) Although this method may result in a more representative sample than the method in part a) , this is still a voluntary response sample. Only strongly motivated parents attend PTA meetings. c) This is multistage sampling, stratified by elementary school and then clustered by grade. This is a good design, as long as the parents in the class respond. There should be follow-up to get the opinions of parents who do not respond. d) This is systematic sampling. As long as a starting point is randomized, this method should produce reliable data. sources of variability in the long run. 22. Fish. a) This is a multistage design, with one day picked at random as a cluster, then 5 boats picked at random as clusters within that day, and finally, a census taken for each boat. b)
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solution_to_chapter_12_13_and_14_problems - Solution to...

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