Chapter 4: Problem 40
Briefly explain why a small value of \(s_{e}\) is desirable in a regression setting.
Chapter 4: Problem 40
Briefly explain why a small value of \(s_{e}\) is desirable in a regression setting.
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Get started for freeData on \(x=\) size of a house (in square feet) and \(y=\) amount of natural gas used (therms) during a specified period were used to fit the least squares regression line. The slope was 0.017 and the intercept was \(-5.0 .\) Houses in this data set ranged in size from 1,000 to 3,000 square feet. a. What is the equation of the least squares regression line? b. What would you predict for gas usage for a 2,100 sq. ft. house? c. What is the approximate change in gas usage associated with a 1 sq. ft. increase in size? d. Would you use the least squares regression line to predict gas usage for a 500 sq. ft. house? Why or why not?
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.
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. Price and weight of an apple b. A person's height and the number of pets he or she has c. Time spent studying for an exam and score on the exam d. A person's weight and the time it takes him or her to run one mile
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.
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