I am trying to decompose the gender wage gap into explained and unexplained factors using the Blinder Oaxaca decomposition technique using labour survey data. For the same, I ran the following command:
oaxaca log_monthlywages_salary_casual num_frml_edu tech_deg exp_n expsq_n mar_18 ss, by(gender) svy pooled
For this I had restricted my sample to wage earners.
After reading more literature I realised the selectivity bias and want to correct using the heckman two step procedure. Since my sample is restricted to wage earners and I had dropped all other categories such as unemployed, not willing to work, self-employed etc my lfpr (dependent variable) for the probit regression for heckman will always be 1. Should I expand the sample for this and then restrict it back for the Oaxaca eqn?