Qreg analysis

[Laura Baika]

Hello,
I am running QREG analysis in STATA to see difference between wages of 2 groups of persons per year. Both of the group variables are dichotomous - indicating whether person belongs to group 1 or group 2.

When I run QREG, I regress:
qreg wage group1 group2 if year == x
grqreg, ci ols ycommon iscale (.5)

However, I am initially interested in GRQREG that shows the differences between group1 and group2, but I do not seem to find a way to do that in STATA using QREG command and GRQREG.

In MACHADO AND MATA "COUNTERFACTUAL DECOMPOSITION OF CHANGES IN WAGE DISTRIBUTIONS USING QUANTILE REGRESSION" they manage to do it, whilst I don't know exactly how (attached a picture).

Would anyone be able to help me?

Best,
Laura

[Rich Goldstein]

if group1 and group2 are both exhaustive (include everyone) and exclusive (no one is in both group1 and group2), then you just need one of them in the model and that will be the difference; e.g.,

qreg wage i.group1 if year==x