Consider the simple linear regression model fit to the copolyester viscosity data in Problem…
Consider the simple linear regression model fit to the copolyester viscosity data in Problem 2.14.
a. Construct a normal probability plot of the unscaled residuals. Does there seem to be any problem with the normality assumption?
b. Repeat part a using the studentized residuals. Is there any substantial difference in the two plots?
c. Construct and interpret a plot of the residuals versus the predicted response.
Problem 2.14
Hsuie, Ma, and Tsai (“Separation and Characterizations of Thermotropic Copolyesters of p-Hydroxybenzoic Acid, Sebacic Acid, and Hydroquinone,” Journal of Applied Polymer Science, 56, 471– 476, 1995) study the effect of the molar ratio of sebacic acid (the regressor) on the intrinsic viscosity of copolyesters (the response). The following table gives the data.
a. Make a scatterplot of the data.
b. Estimate the prediction equation.
c. Perform a complete, appropriate analysis (statistical tests, calculation of R2, and so forth).
d. Calculate and plot the 95% confidence and prediction bands.