generate age2 = age^2 * Combined regression regress sleep totwrk educ age age2 yngkid * Separate male and female regressions regress sleep totwrk educ age age2 yngkid if male == 1 regress sleep totwrk educ age age2 yngkid if male == 0 generate totwrk_male = totwrk*male generate educ_male = educ*male generate age_male = age*male generate age2_male = age2*male generate yngkid_male = yngkid*male * Additive/Multiplicate Dummy equation regress sleep totwrk educ age age2 yngkid male totwrk_male educ_male age_male age2_male yngkid_male * Chow Test test male totwrk_male educ_male age_male age2_male yngkid_male * Joint test of the multiplicative dummies (only a parallel difference in eqs.) test totwrk_male educ_male age_male age2_male yngkid_male