Beineke and Suddarth (1979) and Devore (1991, p. 380) consider data on roof supports involving trusses that use light-gauge metal connector plates. Their dependent variable is an axial stiffness index (ASI) measured in kips per inch. The predictor variable is the length of the light-gauge metal connector plates. The data are given in Table 8.6.

Fit linear, quadratic, cubic, and quartic polynomial regression models using powers of x, the plate length, and using powers of x− ¯ x·, the plate length minus the average plate length. Compare the results of the two procedures. If your computer program will not fit some of the models, report on that in addition to comparing results for the models you could fit.