Refer to Problem 15-9, which referenced an article in BusinessWeek that presented a list of the 100 companies perceived as having “hot growth” characteristics. The file titled 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 Problem 15-9, a regression equation was constructed in which the sales of the companies was predicted using their market value.
a. Determine the estimated regression equation for this data set.
b. Calculate the residuals and the standardized residuals for this regression equation.
c. Produce the appropriate residual plot to determine if the linear function is the appropriate regression function for this data set.
d. Use a residual plot to determine if the residuals have a constant variance.
e. Produce the appropriate residual plot to determine if the residuals are independent. Assume the data were extracted in the order listed.
f. Construct a probability plot to determine if the error terms are normally distributed.