Exam 13: Multiple Regression

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Exhibit 13-3 In a regression model involving 30 observations, the following estimated regression equation was obtained: Exhibit 13-3 In a regression model involving 30 observations, the following estimated regression equation was obtained:   = 17 + 4x<sub>1</sub> - 3x<sub>2</sub> + 8x<sub>3</sub> + 8x<sub>4</sub> For this model SSR = 700 and SSE = 100. -Refer to Exhibit 13-3. The conclusion is that the = 17 + 4x1 - 3x2 + 8x3 + 8x4 For this model SSR = 700 and SSE = 100. -Refer to Exhibit 13-3. The conclusion is that the

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The numerical value of the coefficient of determination

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The following regression model has been proposed to predict monthly sales at a shoe store. The following regression model has been proposed to predict monthly sales at a shoe store.   = 40 - 3x<sub>1</sub> + 12x<sub>2</sub> + 10x<sub>3</sub> where x<sub>1</sub> = competitor's previous month's sales (in $1,000s) x<sub>2</sub> = Stores previous month's sales (in $1,000s)     = sales (in $1000s)  a.Predict sales (in dollars) for the shoe store if the competitor's previous month's sales were $9,000, the store's previous month's sales were $30,000, and no radio advertisements were run. b.Predict sales (in dollars) for the shoe store if the competitor's previous month's sales were $9,000, the store's previous month's sales were $30,000, and 10 radio advertisements were run. = 40 - 3x1 + 12x2 + 10x3 where x1 = competitor's previous month's sales (in $1,000s) x2 = Stores previous month's sales (in $1,000s) The following regression model has been proposed to predict monthly sales at a shoe store.   = 40 - 3x<sub>1</sub> + 12x<sub>2</sub> + 10x<sub>3</sub> where x<sub>1</sub> = competitor's previous month's sales (in $1,000s) x<sub>2</sub> = Stores previous month's sales (in $1,000s)     = sales (in $1000s)  a.Predict sales (in dollars) for the shoe store if the competitor's previous month's sales were $9,000, the store's previous month's sales were $30,000, and no radio advertisements were run. b.Predict sales (in dollars) for the shoe store if the competitor's previous month's sales were $9,000, the store's previous month's sales were $30,000, and 10 radio advertisements were run. The following regression model has been proposed to predict monthly sales at a shoe store.   = 40 - 3x<sub>1</sub> + 12x<sub>2</sub> + 10x<sub>3</sub> where x<sub>1</sub> = competitor's previous month's sales (in $1,000s) x<sub>2</sub> = Stores previous month's sales (in $1,000s)     = sales (in $1000s)  a.Predict sales (in dollars) for the shoe store if the competitor's previous month's sales were $9,000, the store's previous month's sales were $30,000, and no radio advertisements were run. b.Predict sales (in dollars) for the shoe store if the competitor's previous month's sales were $9,000, the store's previous month's sales were $30,000, and 10 radio advertisements were run. = sales (in $1000s) a.Predict sales (in dollars) for the shoe store if the competitor's previous month's sales were $9,000, the store's previous month's sales were $30,000, and no radio advertisements were run. b.Predict sales (in dollars) for the shoe store if the competitor's previous month's sales were $9,000, the store's previous month's sales were $30,000, and 10 radio advertisements were run.

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Below you are given a partial ANOVA table relating the price of a company's stock (y in dollars), the Dow Jones industrial average (x1), and the stock price of the company's major competitor (x2 in dollars). Below you are given a partial ANOVA table relating the price of a company's stock (y in dollars), the Dow Jones industrial average (x<sub>1</sub>), and the stock price of the company's major competitor (x<sub>2</sub> in dollars).     a.What has been the sample size for this regression analysis? b.At <font face=symbol></font> = 0.05 level of significance, test to determine if the model is significant. That is, determine if there exists a significant relationship between the independent variables and the dependent variable. c.Determine the multiple coefficient of determination. a.What has been the sample size for this regression analysis? b.At = 0.05 level of significance, test to determine if the model is significant. That is, determine if there exists a significant relationship between the independent variables and the dependent variable. c.Determine the multiple coefficient of determination.

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In regression analysis, an outlier is an observation whose

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Exhibit 13-4 a. y = 0 + 1x1 + 2x2 + b. E(y) = 0 + 1x1 + 2x2 c.Exhibit 13-4 a. y = <font face=symbol></font><sub>0</sub> + <font face=symbol></font><sub>1</sub>x<sub>1</sub> + <font face=symbol></font><sub>2</sub>x<sub>2</sub> + <font face=symbol></font> b. E(y) = <font face=symbol></font><sub>0</sub> + <font face=symbol></font><sub>1</sub>x<sub>1</sub> + <font face=symbol></font><sub>2</sub>x<sub>2</sub> c. = b<sub>o</sub> + b<sub>1</sub> x<sub>1</sub> + b<sub>2</sub> x<sub>2</sub> d. E(y) = <font face=symbol></font><sub>0</sub> + <font face=symbol></font><sub>1</sub>x<sub>1</sub> + <font face=symbol></font><sub>2</sub>x<sub>2</sub> -Refer to Exhibit 13-4. Which equation gives the estimated regression line?= bo + b1 x1 + b2 x2 d. E(y) = 0 + 1x1 + 2x2 -Refer to Exhibit 13-4. Which equation gives the estimated regression line?

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The correct relationship between SST, SSR, and SSE is given by

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In a residual plot that does not suggest we should challenge the assumptions of our regression model, we would expect to see

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A student used multiple regression analysis to study how family spending (y) is influenced by income (x1), family size (x2), and additions to savings (x3). The variables y, x1, and x3 are measured in thousands of dollars. The following results were obtained. A student used multiple regression analysis to study how family spending (y) is influenced by income (x<sub>1</sub>), family size (x<sub>2</sub>), and additions to savings (x<sub>3</sub>). The variables y, x<sub>1</sub>, and x<sub>3</sub> are measured in thousands of dollars. The following results were obtained.    Coefficient of determination = 0.946  a.Write out the estimated regression equation for the relationship between the variables. b.What can you say about the strength of this relationship? c.Carry out a test of whether y is significantly related to the independent variables. Use a .05 level of significance. d.Carry out a test to see if x<sub>3</sub> and y are significantly related. Use a .05 level of significance. e.Why would a coefficient of determination very close to 1.0 be expected here? Coefficient of determination = 0.946 a.Write out the estimated regression equation for the relationship between the variables. b.What can you say about the strength of this relationship? c.Carry out a test of whether y is significantly related to the independent variables. Use a .05 level of significance. d.Carry out a test to see if x3 and y are significantly related. Use a .05 level of significance. e.Why would a coefficient of determination very close to 1.0 be expected here?

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A measure of goodness of fit for the estimated regression equation is the

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A regression was performed on a sample of 16 observations. The estimated equation is A regression was performed on a sample of 16 observations. The estimated equation is   = 23.5 - 14.28x<sub>1</sub> + 6.72x<sub>2</sub> + 15.68x<sub>3</sub>. The standard errors for the coefficients are S<sub>b1</sub> = 4.2, S<sub>b2</sub> = 5.6, and S<sub>b3</sub> = 2.8. For this model, SST = 3809.6 and SSR = 3285.4.  a.Compute the appropriate t ratios. b.Test for the significance of <font face=symbol></font><sub>1</sub>, <font face=symbol></font><sub>2</sub>, and <font face=symbol></font><sub>3</sub> at the 5% level of significance. c.Do you think that any of the variables should be dropped from the model? Explain. d.Compute R<sup>2</sup> and R<sub>a</sub><sup>2</sup>. Interpret R<sup>2</sup>. e.Test the significance of the relationship among the variables at the 5% level of significance. = 23.5 - 14.28x1 + 6.72x2 + 15.68x3. The standard errors for the coefficients are Sb1 = 4.2, Sb2 = 5.6, and Sb3 = 2.8. For this model, SST = 3809.6 and SSR = 3285.4. a.Compute the appropriate t ratios. b.Test for the significance of 1, 2, and 3 at the 5% level of significance. c.Do you think that any of the variables should be dropped from the model? Explain. d.Compute R2 and Ra2. Interpret R2. e.Test the significance of the relationship among the variables at the 5% level of significance.

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Exhibit 13-3 In a regression model involving 30 observations, the following estimated regression equation was obtained: Exhibit 13-3 In a regression model involving 30 observations, the following estimated regression equation was obtained:   = 17 + 4x<sub>1</sub> - 3x<sub>2</sub> + 8x<sub>3</sub> + 8x<sub>4</sub> For this model SSR = 700 and SSE = 100. -Refer to Exhibit 13-3. The computed F statistic for testing the significance of the above model is = 17 + 4x1 - 3x2 + 8x3 + 8x4 For this model SSR = 700 and SSE = 100. -Refer to Exhibit 13-3. The computed F statistic for testing the significance of the above model is

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In order to test for the significance of a regression model involving 14 independent variables and 255 observations, the numerator and denominator degrees of freedom (respectively) for the critical value of F are

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A variable that cannot be measured in terms of how much or how many but instead is assigned values to represent categories is called

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Exhibit 13-2 A regression model between sales (y in $1,000), unit price (x1 in dollars) and television advertisement (x2 in dollars) resulted in the following function: Exhibit 13-2 A regression model between sales (y in $1,000), unit price (x<sub>1</sub> in dollars) and television advertisement (x<sub>2</sub> in dollars) resulted in the following function:   = 7 - 3x<sub>1</sub> + 5x<sub>2</sub> For this model SSR = 3500, SSE = 1500, and the sample size is 18. -Refer to Exhibit 13-2. The coefficient of x<sub>2</sub> indicates that if television advertising is increased by $1 (holding the unit price constant), sales are expected to = 7 - 3x1 + 5x2 For this model SSR = 3500, SSE = 1500, and the sample size is 18. -Refer to Exhibit 13-2. The coefficient of x2 indicates that if television advertising is increased by $1 (holding the unit price constant), sales are expected to

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Exhibit 13-2 A regression model between sales (y in $1,000), unit price (x1 in dollars) and television advertisement (x2 in dollars) resulted in the following function: Exhibit 13-2 A regression model between sales (y in $1,000), unit price (x<sub>1</sub> in dollars) and television advertisement (x<sub>2</sub> in dollars) resulted in the following function:   = 7 - 3x<sub>1</sub> + 5x<sub>2</sub> For this model SSR = 3500, SSE = 1500, and the sample size is 18. -Refer to Exhibit 13-2. If we want to test for the significance of the regression model, the critical value of F at 95% confidence is = 7 - 3x1 + 5x2 For this model SSR = 3500, SSE = 1500, and the sample size is 18. -Refer to Exhibit 13-2. If we want to test for the significance of the regression model, the critical value of F at 95% confidence is

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A regression model involving 8 independent variables for a sample of 69 periods resulted in the following sum of squares. SSE = 306 SST = 1800 a.Compute the coefficient of determination. b.At = 0.05, test to determine whether or not the model is significant.

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The following regression model has been proposed to predict sales at a fast food outlet. The following regression model has been proposed to predict sales at a fast food outlet.   = 18 - 2x<sub>1</sub> + 7x<sub>2</sub> + 15x<sub>3</sub> where x<sub>1</sub> = the number of competitors within 1 mile x<sub>2</sub> = the population within 1 mile (in 1,000s) x<sub>3</sub> = 1 if drive-up windows are present, 0 otherwise   = sales (in $1,000s)  a.What is the interpretation of 15 (the coefficient of x<sub>3</sub>) in the regression equation? b.Predict sales for a store with 2 competitors, a population of 10,000 within one mile, and one drive-up window (give the answer in dollars). c.Predict sales for the store with 2 competitors, a population of 10,000 within one mile, and no drive-up window (give the answer in dollars). = 18 - 2x1 + 7x2 + 15x3 where x1 = the number of competitors within 1 mile x2 = the population within 1 mile (in 1,000s) x3 = 1 if drive-up windows are present, 0 otherwise The following regression model has been proposed to predict sales at a fast food outlet.   = 18 - 2x<sub>1</sub> + 7x<sub>2</sub> + 15x<sub>3</sub> where x<sub>1</sub> = the number of competitors within 1 mile x<sub>2</sub> = the population within 1 mile (in 1,000s) x<sub>3</sub> = 1 if drive-up windows are present, 0 otherwise   = sales (in $1,000s)  a.What is the interpretation of 15 (the coefficient of x<sub>3</sub>) in the regression equation? b.Predict sales for a store with 2 competitors, a population of 10,000 within one mile, and one drive-up window (give the answer in dollars). c.Predict sales for the store with 2 competitors, a population of 10,000 within one mile, and no drive-up window (give the answer in dollars). = sales (in $1,000s) a.What is the interpretation of 15 (the coefficient of x3) in the regression equation? b.Predict sales for a store with 2 competitors, a population of 10,000 within one mile, and one drive-up window (give the answer in dollars). c.Predict sales for the store with 2 competitors, a population of 10,000 within one mile, and no drive-up window (give the answer in dollars).

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In order to determine whether or not the number of automobiles sold per day (y) is related to price (x1 in $1,000), and the number of advertising spots (x2), data were gathered for 7 days. Part of the Excel output is shown below. In order to determine whether or not the number of automobiles sold per day (y) is related to price (x<sub>1</sub> in $1,000), and the number of advertising spots (x<sub>2</sub>), data were gathered for 7 days. Part of the Excel output is shown below.     a.Determine the least squares regression function relating y to x<sub>1</sub> and x<sub>2</sub>. b.If the company charges $20,000 for each car and uses 10 advertising spots, how many cars would you expect them to sell in a day? c.At <font face=symbol></font> = 0.05, test to determine if the fitted equation developed in Part a represents a significant relationship between the independent variables and the dependent variable. d.At <font face=symbol></font> = 0.05, test to see if <font face=symbol></font><sub>1</sub> is significantly different from zero. e.Determine the multiple coefficient of determination. a.Determine the least squares regression function relating y to x1 and x2. b.If the company charges $20,000 for each car and uses 10 advertising spots, how many cars would you expect them to sell in a day? c.At = 0.05, test to determine if the fitted equation developed in Part a represents a significant relationship between the independent variables and the dependent variable. d.At = 0.05, test to see if 1 is significantly different from zero. e.Determine the multiple coefficient of determination.

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The following is part of the results of a regression analysis involving sales (y in millions of dollars), advertising expenditures (x1 in thousands of dollars), and number of salespeople (x2) for a corporation. The regression was performed on a sample of 10 observations. The following is part of the results of a regression analysis involving sales (y in millions of dollars), advertising expenditures (x<sub>1</sub> in thousands of dollars), and number of salespeople (x<sub>2</sub>) for a corporation. The regression was performed on a sample of 10 observations.     a.Write the regression equation. b.Interpret the coefficients of the estimated regression equation found in Part (a). c.At <font face=symbol></font> =0.05, test for the significance of the coefficient of advertising. d.At <font face=symbol></font> =0.05, test for the significance of the coefficient of number of salespeople. e.If the company uses $50,000 in advertisement and has 800 salespersons, what are the expected sales? Give your answer in dollars. a.Write the regression equation. b.Interpret the coefficients of the estimated regression equation found in Part (a). c.At =0.05, test for the significance of the coefficient of advertising. d.At =0.05, test for the significance of the coefficient of number of salespeople. e.If the company uses $50,000 in advertisement and has 800 salespersons, what are the expected sales? Give your answer in dollars.

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