Consider the simple linear regression model fit to the copolyester viscosity data in Problem 2.14.

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. 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.

Transcribed Image Text:

Ratio Viscosity 1.0 0.45 0.9 0.20 0.8 0.34 0.7 0.58 0.6 0.70 0.5 0.57 0.4 0.55 0.3 0.44