Chapter 5

Transformations and Weighting to Correct Model Inadequacies

5.1 a. It has a nonlinear pattern.
b. While R2 = 96%, the residual plot shows a nonlinear pattern and normality is violated.
c. There is a slight improvement in the model.
5.2 a. There is a nonlinear pattern.
b. There is a problem with normality and a nonlinear pattern in the residuals.
c. There is a slight improvement in the model.
5.3 a. There is a nonlinear pattern.
b. There is a problem with normality and a nonlinear pattern in the residuals. Observation 1 is an outlier.
c. Fit the number of bacteria versus the natural log of the minutes. The first observation is still an outlier but otherwise the model fits fine.
5.4 The scatterplot looks fine. There is a problem with normality and the residual plot does not look good. Taking the natural log of x makes for a better model.
5.5 a. = −31.698 + 7.277 ...

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