Hi there, I am new to STATALIST so my apologies if this question has already been addressed.

I am using LSAC preschool data with two separate cohorts - the birth cohort (who enter preschool in 2008) and the kindergarten cohort (who enter preschool in 2004) , thus, the treatment and control groups are different children from different time periods.
NSW implemented a policy reform in 2006 which only impacts the B-cohort and not the K-cohort, so naturally, I have a treatment and control group here


I have cleaned the data & using append to combine the cohorts into my do.file, but I am unsure how to run the DID due to having the two cohorts.
Is there a way to specify my control group as well as my separate treatment group?

I know that this is incorrect, but is there a command that will allow me to do something along the lines of this?

interactionB = NSW*Bcohort
interactionK = NSW*Kcohort

diff y3naplan1, t(interactionB) control(interactionK) p(t)

Or will I just have to run the regressions separately and calculate the difference itself by hand?


Any help would be greatly appreciated as this is for my thesis!
Laura