# e1answersfall07 - STA 103 Exam 1 Fall 2007 I. H. Dinwoodie...

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STA 103 Exam 1 Fall 2007 I. H. Dinwoodie NAME: answers Calculator allowed, closed book.

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STA103 Fall 2007 E1 1 Circle True or False. (1 point each) 1. A researcher went to Smalltown and sampled 1000 people for her study on how smoking aFects the cost of healthcare. The researcher noted the value of three variables: Smoker (yes or no), Age (in years), and Health Care Costs in 2006. (a) F This study is a “randomized experiment” with random assignment to smoking and nonsmoking groups. (b) T This study is an “observational study.” (c) F This study is a “double blind” experiment. (d) F If the average health care cost for the subjects in the smoking group turns out to be higher than for the nonsmokers, one may conclude that smoking causes higher health care costs. (e) F If Age is not of primary interest, it may be removed from the data without loss of relevant information. (f) T The relationship between smoking and health care costs may be confused by omitting the Age variable. (g) T Age is called a “confounding” variable. (h) T It may turn out that the overall average health care costs for the smokers is lower than for the nonsmokers, while smoking raises health care costs for each age group, if smoking is more prevalent in younger subjects.
STA103 Fall 2007 E1 2 For questions 2-5, give short numerical answers. (3 points each)

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## This note was uploaded on 09/29/2008 for the course STAT 103 taught by Professor Dinwoodie during the Fall '08 term at Duke.

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e1answersfall07 - STA 103 Exam 1 Fall 2007 I. H. Dinwoodie...

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