**1) What is the purpose of the relevel function for variables with more than 2 categories.**

I understand that you select one category for the "base", and the other categories are compared to it. But why is it necessary?

**2) How you do you interpret the coefficient estimates of a GLM model of a variable that has been re-leveled?**

example:

Coefficients:

Estimate Std. Error z value Pr(>|z|)

(Intercept) 2.49805 0.79386 3.147 0.001651 **

Category1 0.32993 0.67235 0.491 0.623637

Category2 -1.38851 0.35765 -3.882 0.000103 ***

Category3 -1.74476 0.42517 -4.104 4.07e-05 ***