Chapter 13: Problem 2
Explain the meaning of independent and dependent variables for a regression model.
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Chapter 13: Problem 2
Explain the meaning of independent and dependent variables for a regression model.
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A population data set produced the following information. $$ N=460, \quad \Sigma x=3920, \quad \Sigma y=2650, \quad \Sigma x y=26,570, \quad \Sigma x^{2}=48,530 $$ Find the population regression line.
Refer to Exercise \(13.25\). The data on ages (in years) and prices (in hundreds of dollars) for eight cars of a specific model are reproduced from that exercise. $$ \begin{array}{l|rrrrrrrr} \hline \text { Age } & 8 & 3 & 6 & 9 & 2 & 5 & 6 & 3 \\ \hline \text { Price } & 45 & 210 & 100 & 33 & 267 & 134 & 109 & 235 \\ \hline \end{array} $$ a. Do you expect the ages and prices of cars to be positively or negatively related? Explain. b. Calculate the linear correlation coefficient. c. Test at the \(2.5 \%\) significance level whether \(\rho\) is negative.
A sample data set produced the following information. $$ \begin{aligned} &n=12, \quad \Sigma x=66, \quad \Sigma y=588, \quad \Sigma x y=2244, \\ &\Sigma x^{2}=396, \quad \text { and } \quad \Sigma y^{2}=58,734 \end{aligned} $$ a. Calculate the linear correlation coefficient \(r\). b. Using the \(1 \%\) significance level, can you conclude that \(\rho\) is negative?
A population data set produced the following information. $$ \begin{aligned} &N=460, \quad \Sigma x=3920, \quad \Sigma y=2650, \quad \Sigma x y=26,570 \\ &\Sigma x^{2}=48,530, \text { and } \Sigma y^{2}=39,347 \end{aligned} $$ Find the linear correlation coefficient \(\rho\).
Consider the data given in the following table. $$ \begin{array}{l|llllll} \hline x & 10 & 20 & 30 & 40 & 50 & 60 \\ \hline y & 12 & 15 & 19 & 21 & 25 & 30 \\ \hline \end{array} $$ a. Find the least squares regression line and the linear correlation coefficient \(r\). b. Suppose that each value of \(y\) given in the table is increased by 5 and the \(x\) values remain unchanged. Would you expect \(r\) to increase, decrease, or remain the same? How do you expect the least squares regression line to change? c. Increase each value of \(y\) given in the table by 5 and find the new least squares regression line and the correlation coefficient \(r\). Do these results agree with your expectation in part b?
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