11.40 A researcher wanted to investigate the effects of several factors on production-line supervisors’

attitudes toward handicapped workers. A study was conducted involving 40 randomly selected supervisors. The response Y, a supervisor’s attitude toward handicapped workers, was measured with a standardized attitude scale.

Independent variables used in the study were supervisory job x2 = number of years of experiences in a x1 = e 1 if the supervisor is female 0 if the supervisor is male The researcher fit the model to the data with the following results:
a Do these data provide sufficient evidence to indicate that the quadratic term, years of experience , is useful for predicting attitude score? Use .
b Sketch the predicted attitude score as a function of the number of years of experience for male supervisors . Next, substitute into the least-squares equation and obtain a plot of the prediction equation for female supervisors. [Note: For both males and females, plotting for , and 10 will produce a good picture of the prediction equations. The vertical distance between the males’ and females’ prediction curves is the same for all values of .]