Refer to Exercise 15-8, which referenced a list of the 100 companies perceived as having “hot growth” characteristics.

The file entitled Logrowth contains sales

($million), sales increase (%), return on capital, market value ($million), and recent stock price of the companies ranked from 81 to 100. In Exercise 15-8, stock prices were the focus. Examine the sales of the companies.

a. Produce a regression equation that will predict the sales as a function of the other variables.

b. Determine if the overall model is significant. Use a significance level of 0.05.

c. Conduct a test of hypothesis to discover if market value should be removed from this model.

d. To see that a variable can be insignificant in one model but very significant in another, construct a regression equation in which sales is the dependent variable and market value is the independent variable. Test the hypothesis that market value is a significant predictor of sales for those companies ranked from 81 to 100. Use a significance level of 0.05 and the p-value approach.