Chapter 4: Problem 12
Draw two scatterplots, one for which \(r=1\) and a second for which \(r=-1\).
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Chapter 4: Problem 12
Draw two scatterplots, one for which \(r=1\) and a second for which \(r=-1\).
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In a study of the relationship between TV viewing and eating habits, a sample of 548 ethnically diverse students from Massachusetts was followed over a 19 -month period (Pediatrics [2003]: 1321-1326). For each additional hour of television viewed per day, the number of fruit and vegetable servings per day was found to decrease on average by 0.14 serving. a. For this study, what is the response variable? What is the predictor variable? b. Would the least squares regression line for predicting number of servings of fruits and vegetables using number of hours spent watching TV have a positive or negative slope? Justify your choice.
For each of the following pairs of variables, indicate whether you would expect a positive correlation, a negative correlation, or a correlation close to \(0 .\) Explain your choice. a. Interest rate and number of loan applications b. Height and \(\mathrm{IQ}\) c. Height and shoe size d. Minimum daily temperature and cooling cost
For each of the following pairs of variables, indicate whether you would expect a positive correlation, a negative correlation, or a correlation close to \(0 .\) Explain your choice. a. Weight of a car and gas mileage b. Size and selling price of a house c. Height and weight d. Height and number of siblings
Briefly explain why it is important to consider the value of \(r^{2}\) in addition to the value of \(s\) when evaluating the usefulness of the least squares regression line.
A sample of automobiles traveling on a particular segment of a highway is selected. Each one travels at roughly a constant rate of speed, although speed does vary from auto to auto. Let \(x=\) speed and \(y=\) time needed to travel this segment. Would the sample correlation coefficient be closest to \(0.9,0.3,-0.3,\) or \(-0.9 ?\) Explain.
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