Estimate a part of a data set

[Heidi Ph]

Hello!

In the data set I have the variable: "college" = 1 if student went to college, 0 otherwise; and "period" =2 for 2nd period, and =1 for the 1st period; and "degree" =1 for getting high school degree, =0 otherwise; and some other variables relating the characteristic of the student.

So, I want to estimate utility from going to college but conditional on student having obtained the high school degree, and in period 2 only.

I can do it by simply drop out observations of 1st period and students who did not obtained a high school degree. But I do not want to do so, since I still need the whole data set for other regression.

Is there any way to proceed without dropping out observations?

Thank you,

[Maarten Buis]

You can use an if condition to most commands in Stata. type in Stata help if

[Heidi Ph]

Thanks for your reply. I just tried it, and figure out a way to do it like:
logit school (some variables) if degree=1 & period==2.
Is this correct?