StatisticsQuiz1Answers - Spring2009 Statistics Quiz 1 1. A...

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Spring 2009 1 Statistics Quiz 1 1. A researcher determines that he needs results from at least 350 subjects to conduct a study. In order to compensate for low return rates, he mails a survey to 10,000 subjects and receives 391 responses. Is his sample of 391 responses a good sample? Explain you answer. No - This sample of 391 respondents is not a good sample. The biggest problem with this sample is that it is a self-selected sample. We only observe responses for people who bothered to read the mailing that the researcher sent out, and then bothered to respond to the survey. The people who responded to this survey are likely to have different characteristics than a truly random sample (e.g. they might be more likely to be unemployed or out of the labor force . .. hence they have the time to read this survey and send a response). Only 391 out of 10,000 people bothered to respond. This should make us especially worried. The vast majority of people did not choose to respond. The people that did respond might have very unique characteristics. 2. After constructing a relative frequency distribution summarizing IQ scores of college students, what should be the sum of the relative frequencies? If the percentages are used, the sum should be_____100%________. If proportions are used, the sum should be ____1___________. 3. The data represents the daily rainfall (in inches) for one month.

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This note was uploaded on 04/07/2012 for the course STATS V31.0018.0 taught by Professor Thom during the Spring '10 term at NYU.

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StatisticsQuiz1Answers - Spring2009 Statistics Quiz 1 1. A...

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