st: RE: new var from an old one if a third var has a certain value

[Nick Cox <n.j.cox@durham.ac.uk>]

There is a very direct answer: 

. gen var3 = var1 if var2 == whatever

You are also not far away from 

. gen var3 = cond(var2 == whatever, var1, .) 

Using -cond()- has no advantages for this problem -- except perhaps that some people might like it being explicit that missing is the value supplied when var2 != whatever. 

However, watch out. Tests for equality are only reliable when <whatever> is an integer (or a string). 

Nick 
n.j.cox@durham.ac.uk 

Caterina Astarita

I need to generate a new variable that have the values of an 
old one if a third variable has a certain value, othewise a 
missing value. 

Let's say we have two variables var1 and var2, I would like to 
generate a var3 that has the value of var1 but only if var2 
has a certain value otherwise not. 


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