 average marginal effects of skin thickness vary less than those for age. Yet, the AME of skin thickness is as high as 2% when age is low and skin thickness is high. Interestingly, however, this effect actually becomes negative as age increases. The marginal effect of skin thickness is radically different for young and old women.</p>
<p>For either of these cases, it would also be appropriate to draw two-dimensional plots of “slides” of these surfaces and incorporate measures of uncertainty. It is extrem