using if for regression

[rbriceno]

Hello. I have a panel data with 337 cross sections and 256 time series. One of the things that I'm trying to do is to run regressions for some specific cross-sections. I tried with:

if id=1 then
equation eq1.ls liq c sap
endif

but nothing happened. I'm not clear about the way if statement works, and I would like get some insight from you. I have a doub also about the wat the ifs can be combined (for example if id=1 and year=2009). Thanks.

[EViews Gareth]

You need to use the smpl command to set the sample to be used for the equation.