In a regression model with dummy variables:
For example, I would like to test the relationships between occupation types and salary. In this condition, occupation is a categorical variable with 4 types (i.e., occ1; occ2; occ3 and occ4); salary is a continuous variable.
In the regression model to test the relationships between occupation types and salary, I regard occ4 as the reference group, valued occ4 as "0", and valued the other three occupation types (occ1, occ2, and occ3) as "1" respectively. To sum up, in this regression model, I got three dummy variables (i.e., occ1=1/occ2=1/occ3=1).
In this vein, I run the regression model with three dummy variables and got the regression formula like: Y(salary)= B0+Bocc1X+Bocc2X+Bocc3X+error. In this model, Bocc1, Bocc2 and Bocc3 is calculated by comparing to the referent group (i.e., occ4). However, if I would like to compare two coefficients (e.g., Bocc1 and Bocc2), how should I implement it through JMP? Should I use t-test? but how to achieve it?
Many thanks indeed for your help.