st: Deleting variables for lack of observations

[John Hennen <jhennen@mclean.org>]

Joel Clovis wrote:

> I want to delete variables if they do not contain enough observatoins.  I've
> tried to make use of Nick Coxs'  npresent & dropmiss (STB-49:dm67 &
> STB-60: dm89)  to no avail, some attempts are in the following manner:
>
> foreach var of varlist cba2tfina-region {
>             keep `var' if r(npresent)>=30
>     }

>
> this brings up invalid syntax, and I'm not sure why
>

REPLY-
Assuming that the several variables in the varlist cba2tfina - region are not
strings, did you want something like this:

foreach var of varlist cba2tfina-region {
            qui npresent `var'
            replace `var' = .  if r(N) <30
    }

John Hennen
Boston


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