Keep if

[Fernando Bastidas]

Hi guys!

In my database I have a panel data of results of a test for multiple schools. However I have to work with 47 of them and each school has a unique id to identify each one. RBD is de ID of each school so I wanted to use the keep if command and write the every id of the 47 schools that I'm working with.

keep if rbd==7929 | rbd==7987 | rbd==7874 | rbd==7887 | rbd==7927 | rbd=7968 | (...)

However after the sixth condition, stata shows me an error

=exp not allowed
r(101);

I don't know what the problem is, so I'd really appreciate your help.

Thanks!

[Nick Cox]

Typo: you need

 
 rbd==7968

not

  
 rbd=7968 

However, check out

inlist()

e.g. https://www.stata-journal.com/articl...article=dm0026 and https://www.stata.com/support/faqs/d...s-for-subsets/

[Bruce Weaver]

Hello Fernando. You said in #1 that you want to keep 47 schools. How many schools do you want to exclude? I ask, because if the number you want to exclude is lower, you can shorten your code by using -drop- with the shorter list rather than -keep- with the longer list.

keep if inlist(rbd, comma-separated list of rbd values to keep)
drop if inlist(rbd, comma-separated list of rbd values to drop)