(1 point) For each problem, select the best response. (a) When possible, the bes
ID: 3052557 • Letter: #
Question
(1 point) For each problem, select the best response. (a) When possible, the best way to establish that an observed association is the result of a cause-and-effect relation is by means of A. the square of the correlation coefficient. B. a well designed experiment. C. the correlation coefficient. D. the least squares regression line. E. None of the above. (b) A researcher observes that, on average, the number of divorces in cities with major league baseball teams is larger than in cities without major league baseball tearms. The most plausible explanation for this observed association is n is due to the presence of a lurking variable (major league teams tend to be in large cities with more people, hence coincidental. It is implausible to believe the observed association could be anything other than a greater number of divorces), B. the observed association is purely accidental C. the high number of divorces is responsible for the presence of a major league baseball teams (more single men means potentially more fans at the ballpark, making it attractive for an owner to relocate to such cities) D. the presence of a major league baseball team causes the number of divorces to rise (perhaps husbands are spending too much time at the ballpark). E. None of the above. (c) The owner of a chain of supermarkets notices that there is a positive correlation between the sales of beer and the sales of ice cream over the course of the previous year. Seasons when sales of beer were above average, sales of ice cream also tended to be above average. Likewise, during seasons when sales of beer were below average, sales of ice cream also tended to be below average. Which of the following would be a valid conclusion from these facts? A. A scatterplot of monthly ice cream sales versus monthly beer sales would show that a straight line describes the pattern in the plot, but it would have to be a horizontal line. B. The sale of beer and ice cream may both be affected by another variable such as the outside termperature. C. Sales records must be in error. There should be no association between beer and ice cream sales. D. Evidently, for a significant proportion of customers of these supermarkets, drinking beer causes a desire for ice cream or eating ice cream causes a thirst for beer E. None of the above.Explanation / Answer
Solution
(1) Option (b) a well designed experiment
(2) (a) association is due to the presence of a lurking variable (Major League teams tend to be in
large cities with more people, hence a greater number of divorces)
(3) (b) The sale of beer and ice cream may both be affected by another variable such as the outside temperature
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