Re: st: Egen functions - preserving missing values?

["Michael Blasnik" <michael.blasnik@verizon.net>]

Why not just two steps:

egen fam_inc = total(income), by(family)
bysort family (income): replace fam_inc=. if income[1]==.

Michael Blasnik
michael.blasnik@verizon.net


----- Original Message ----- 
From: "Eric G. Wruck" <ewruck@econalytics.com>
To: <statalist@hsphsun2.harvard.edu>
Sent: Thursday, October 06, 2005 4:32 PM
Subject: Re: st: Egen functions - preserving missing values?



> On September 28th, I posted something quite similar entitled "Collapse & 
> Missing Values".  A few people chimed in with their thoughts & ideas. 
> Basically, there is not an easy way around this problem.  But here is one 
> that I think works:
<snip>
> . egen fam_inc = total(income), by(family)
> . egen no_miss = total(cond(income==.,1,0)), by(family)
> . egen no_nmiss = total(cond(income~=.,1,0)), by(family)
<snip>
> . replace fam_inc = . if fam_inc == 0 & no_miss > 0 & no_nmiss == 0
> (5 real changes made, 5 to missing)
<snip>
> Kind of kludgy, I know.  What I'd really like to see Stata at least offer 
> an option on collapse & egen that would not do this, but Nick Cox rather 
> dashed my hopes on that front.  But perhaps someone can write a routine 
> that would automate this?
>
> Best of luck,
>
> Eric
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