Chapter 13: Problem 8
Explain the least squares method and least squares regression line. Why are they called by these names?
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Chapter 13: Problem 8
Explain the least squares method and least squares regression line. Why are they called by these names?
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A researcher took a sample of 10 years and found the following relationship between \(x\) and \(y\), where \(x\) is the number of major natural calamities (such as tornadoes, hurricanes, earthquakes, floods, etc.) that occurred during a year and \(y\) represents the average annual total profits (in millions of dollars) of a sample of insurance companies in the United States. $$ \hat{y}=342.6-2.10 x $$ a. A randomly selected year had 24 major calamities. What are the expected average profits of U.S. insurance companies for that year? b. Suppose the number of major calamities was the same for each of 3 years. Do you expect the average profits for all U.S. insurance companies to be the same for each of these 3 years? Explain. c. Is the relationship between \(x\) and \(y\) exact or nonexact?
The following information is obtained from a sample data set. $$ n=10, \quad \Sigma x=100, \quad \Sigma y=220, \quad \Sigma x y=3680, \quad \Sigma x^{2}=1140 $$ Find the estimated regression line.
The following table gives information on the number of megapixels and the prices of nine randomly selected point-and-shoot digital cameras that were available on BestBuy.com on July 22, 2009 . $$ \begin{array}{l|rrrrrrrrr} \hline \text { Megapixels } & 10.3 & 10.2 & 7.0 & 9.1 & 10.0 & 12.1 & 8.0 & 5.0 & 14.7 \\ \hline \text { Price (\$) } & 130 & 150 & 62 & 160 & 200 & 280 & 125 & 60 & 400 \\ \hline \end{array} $$ Compute the following. a. \(\mathrm{SS}_{\mathrm{xr}} \mathrm{SS}_{y,}\) and \(\mathrm{SS}_{x y}\) b. Standard deviation of errors c. SST, SSE, and SSR d. Coefficient of determination
Explain the difference between linear and nonlinear relationships between two variables.
For a sample data set, the linear correlation coefficient \(r\) has a positive value. Which of the following is true about the slope \(b\) of the regression line estimated for the same sample data? a. The value of \(b\) will be positive. b. The value of \(b\) will be negative. c. The value of \(b\) can be positive or negative.
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