Dear all,

I have two groups and have tested whether the mean of my variable of interest is significantly different in each of two periods (using the ttest command; i.e. ttest "var" if year==1, by(treated) and ttest "var" if year==2, by(treated). However, I would also like to test whether the difference between those differences themselves is statistically significant (i.e. a get a raw diff-in-diff estimate); is it possible to do this without a regression?

Many thanks!