At fixed intrinsic ratio , part a gives
Since is uniform, the change-of-variables formula for a probability density yields the conditional probability density function
The inverse-square-root singularity at is integrable, and direct integration gives one.
The printed values appear to favor model 2 because . They are not directly comparable: model 2 reports the Gaussian likelihood of , whereas model 3 reports a density for . The change-of-variables formula for a probability density gives
so the transformed model's AIC on the original response scale is
Because the standardized predictors have zero sample means and the ordinary-least-squares residuals sum to zero,
Therefore
which is slightly worse than model 3's .
For an unoriented symmetry axis chosen uniformly on the sphere, is uniform on . At fixed intrinsic ratio , the change-of-variables formula for a probability density gives