Homework Week 5- Magazines
ProTutor11
question_hw_week_5.docHomework Week 5
A little statistics humor. Get it?
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The attached data file (Magazines.xls) contains the hours per month spent telemarketing and the number of new subscriptions per month over a two-year period for a magazine publisher. The publisher would like to predict the number of new subscriptions based on the hours spent telemarketing.
Use the data to create a scatterplot; add a trendline; request the regression line equation and the r-squared value. (You do not have to submit the scatterplot but you will need it to answer Questions 1 – 6 below.)
HINT: Make sure the explanatory variable is on the x-axis.
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1. Describe the overall pattern of the relationship between hours spent telemarketing and number of new subscriptions.
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2. What is the correlation between hours spent telemarketing and number of new subscriptions? [numerical answer required] |
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3. What is the equation for the least squares regression line? [Note: The OLI materials give the equation in the form Y = a + bx But Excel presents the equation as Y = bx + a. It doesn’t matter which way you express it as long as it is correct and you can distinguish between the intercept and the slope.] |
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4. If telemarketing hours increase by one hour, we would expect the number of new subscriptions to _________ by ____________.
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5. Predict the number of subscriptions for a month in which there were 900 hours of telemarketing. |
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6. Explain why it would not be a good idea to predict the number of subscriptions for a month in which there were 1600 hours of telemarketing. |
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7. A researcher found that the relationship between the appraised value of a house (in thousands of dollars) and its age (in years) could be summarized by the regression equation: Appraised value = 400.8 - 2.5 * age. Interpret the value of the slope in the context of this study.
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8. A medical researcher asks: What is the effect of age on blood pressure? Identify the explanatory and response variables.
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9. Use the graph below to predict the test score for a student who studied for 15 hours.
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10. In New York State there is a fairly strong positive correlation between principals’ salaries and the reading scores of their students. (This is true.) Upon learning this, a politician recommends that principals’ salaries be increased because this will cause students’ reading scores to increase. Good idea? (Explain your answer.) |
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