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Corvette Prices. Following are the age and price data for Corvettes from Exercise 4.59:

a. Compute SST,SSR,SSE

b. Compute the coefficient of determination

c. Determine the percentage of variation in the observed values of the response variable explained by the regression, and interpret your answer.

d. State how useful the regression equation appears to be for making predictions.

Short Answer

Expert verified

(a)SST=25681.6SSR=24057.8913SSE=1623.7087

(b)0.9368

(c)93.68%

(d) Utilising the regression equation to create predictions is quite effective, and the regression can explain roughly 94%of the variation.

Step by step solution

01

Part (a) Step 1: Given information

The given data is

02

Part (a) Step 2: Explanation

The below table gives the prices of randomly selected 10Corvettes with their age between 1 and 6 years inclusively. The age is denoted by x, and the price is denoted by yin hundreds of dollars.

The formulas to calculate the sum of squares is

SST=∑yi2-∑yi2/n

SSR=∑xiyi-∑xi∑yi/n2∑xi2-∑xi2/n

SSE=SST-SSR

As shown in the table below, the relevant sums can be determined.

SST=1196690-3422210

localid="1653298850723" =25681.6

SSR=|13168-41×3422÷10|2199-4⌋2÷10SSR=24057.8913

SSE=25681.6-24057.8913SSE=1623.7087

03

Part (b) Step 1: Given information

The given data is

04

Part (b) Step 2: Explanation

The coefficient of determination is

r2=SSRSST

=24057.891325681.6=0.9368

05

Part (c) Step 1: Given information

The given data is

06

Part (c) Step 2: Explanation

The coefficient of determination restated as a percentage is the percentage of variation:

0.9368=93.68%

07

Part (d) Step 1: Given information

The given data is

08

Part (d) Step 2: Explanation

The regression equation can be used to generate predictions if the estimated r2is near to 1.

The computed r2=0.9368, which is extremely near to 1.

As a result, utilising the regression equation to create predictions is quite effective, and the regression can explain roughly 94% of the variation.

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Most popular questions from this chapter

Corvette Prices. In Exercise 4.59. you determined a regression equation that can be used to predict the price of a Corvette, given its age.

a. Should that regression equation be used to predict the price of a 4-year-old Corvette? a 10-year-old Corvette? Explain your answers.

b. For which ages is the use of the regression equation to predict price reasonable?

9. Based on the least-squares criterion, the line that best fits a set of data points is the one with the ________possible sum of squared errors.

Shortleaf Mines. The ability to estimate the volume of a tree based on a simple measurement, such as the tree's diameter, is important to the lumber industry, ecologists, and conservationists. Data on volume, in cubic feet. and diameter at breast height, in inches, for 70shortlist pics were reported in C. Bruce and F. X. Schumacher's hopes Mensuration (New York: McGraw-Hill. 1935) and analyzed by A. C. Atkinson in the article "Transforming Both Sides of a Tree" (The Anarricas Slasisiciun, Vol, 48, PD. 307-312), The data are presented on the WeissStats site.

a. Obtain a scatterplot for the dater.

h. Decide whether finding a depression lime for the data is reasonable. If so, then also do jurras (e) (f.

Sample Covariance. For a set of n data points, the sample covariance, sxy+is given by

The sample covariance can be used as an alternative method for tinding the slope and y-intercept of a regression line. The formulas are

b1=sv/xk2andb0=y^-b1i^n

where sidenotes the sample standard deviation of the x-values.

a. Use Equation (4.1) to determine the sample covariance of the data points in Exercise 4,45.

b. Use Equation (4.2) and your answer from part (a) to find the regression equation. Compare your result to that found in Exercise 4.57.

In Exercise 4.9, we give linear equations. For each equation,

a. find the y-intercept and slope.

b. determine whether the line slopes upward, slopes downward, or is horizontal, without graphing the equation.

c. use two points to graph the equation.

Given equation is,

y=0.5x-2

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