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Test3.Summer2010

Test3.Summer2010 - STAT 3000 Test 3(100 points Summer 2010...

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STAT 3000 Test 3 (100 points) Summer 2010 NAME 1. A researcher wishes to determine whether the rate of water flow (in liters per second) over an experimental soil bed can be used to predict the amount of soil washed away (in kilograms). The researcher measures the amount of soil washed away for various flow rates, and from these data calculates the least-squares regression line to be 0.4 1.3 soil flowrate = + . The correlation between amount of eroded soil and flow rate would be a. 0.4 b. 1.3 c. positive, but we cannot say what the exact value is. d. either positive or negative. It is impossible to say anything about the correlation from the information given. 2. 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 teams. The most plausible explanation for this observed association is a. 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). b. 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). c. the 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). d. the observed association is purely coincidental. It is implausible to believe the observed association could be anything other than accidental. 3. Constructing a scatterplot of residuals against x or predicted y values can be used to check which of the following conditions and/or assumptions? I. Linearity Condition II. Independence Assumption III. Equal Variance Assumption 1
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IV. Normal Population Assumption QUESTIONS 4-5: A well known coffee chain locates shops on or near college campuses. Data were collected to determine if campus size and annual sales were related.
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