# Question

The students in a training program have taken four tests along with a final exam, with the scores shown in the table. The data are also in file XR17071.

a. Construct the correlation matrix for these variables. Does it appear that multicollinearity could be a problem if all of the independent variables are used in estimating y = final exam score? In a stepwise regression, which independent variable would be the first one introduced into the equation, and why?

b. With y = final exam score and the independent variables as shown above, apply stepwise regression analysis to these data.

c. Describe each step of the stepwise regression in terms of the variable introduced, the regression equation after its introduction, and the pro portion of variation in y that has been explained.

d. Using only the independent variables introduced during the stepwise regression, carry out a conventional multiple regression analysis on the data. What, if any, additional information does your computer statistical package provide that was not given in the printout for the stepwise regression?

We suggest that Minitab users specify alpha-to-enter as 0.05 and alpha-to-remove as 0.10.

a. Construct the correlation matrix for these variables. Does it appear that multicollinearity could be a problem if all of the independent variables are used in estimating y = final exam score? In a stepwise regression, which independent variable would be the first one introduced into the equation, and why?

b. With y = final exam score and the independent variables as shown above, apply stepwise regression analysis to these data.

c. Describe each step of the stepwise regression in terms of the variable introduced, the regression equation after its introduction, and the pro portion of variation in y that has been explained.

d. Using only the independent variables introduced during the stepwise regression, carry out a conventional multiple regression analysis on the data. What, if any, additional information does your computer statistical package provide that was not given in the printout for the stepwise regression?

We suggest that Minitab users specify alpha-to-enter as 0.05 and alpha-to-remove as 0.10.

## Answer to relevant Questions

Repeat parts (b)–(d) of Exercise 17.71, with Test 1 as the dependent variable, and Test 2, Test 3, Test 4, and Final Exam as the independent variables. In exercise b. With y = final exam score and the independent variables ...They are coded according to the scheme described in Section 17.4. For a technology company, technology = 1 and the other dummy variables will be 0. For a financial services company, financial = 1 and the others will be 0. If ...The following data describe the monthly volume for an urban courier service. Data are in thousands of pieces handled. a. Construct a graph of the time series. Does the overall trend appear to be upward or downward? b. ...The state of Texas has reported the following quarterly gross sales for the in-state accommodation and food services industry for the years 2004–2008. a. Construct the four-quarter centered moving average for these data ...The U.S. trade deficit with Canada (billions of dollars) from 2000 through 2007 is reported as shown in the table. Using exponential smoothing and the smoothing constant α = 0.7, what deficit would have been forecast for ...Post your question

0