Dear All, I run a DID regression with the following command (the first one is working, but the second one isn't)
Code:
xi: reg flnpat110 c.ingroup##c.inyear, robust
xi: reg flnpat110 i.ingroup##i.inyear, robust
with results being

Array

Note that, both `ingroup' and `inyear' are dummy (binary) variables (have been checked!). Any suggestions for the error message? (I am aware that xi: prefix is not necessary here.)