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Re: st: AW: "skipping" missing data


From   Nick Cox <n.j.cox@stata.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: AW: "skipping" missing data
Date   Thu, 06 Aug 2009 11:28:05 -0500

Here is one of several alternatives.

generate p1=.
egen group = group(ptnum) if !missing(bperwk_, wk)
summarize group, meanonly

forval i = 1/`r(max)' {
 	regress bperwk_ wk if group == `i'
 	predict p
 	replace p1=p if group == `i'
 	drop p
}

That sets the missings on one side.

See also:

FAQ . . . . . . . . . . Making foreach go through all values of a variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox
        8/05    Is there a way to tell Stata to try all values of a
                particular variable in a foreach statement without
                specifying them?
                http://www.stata.com/support/faqs/data/foreach.html

Despite the reference to -foreach- the FAQ is still pertinent.

Nick

Martin Weiss wrote:

*************
capture
*************

You could put it in front of individual commands, or the entire -forvalues-
loop.

B. Timothy Walsh

I am attempting to generate predictions from regressions performed for each of a longish list of individuals. The problem is that, for some individuals, there are no dependent variable data (entries are missing), so the regression attempt fails. The problem is that the forvalues loop then exits. I would like to somehow "skip" these individuals. Loop seems to work fine if there are enough data to perform a regression. I'd be grateful for any suggestions.

Here's the code:
generate p1=.
forvalues i = 1/50 {		//50 individuals
	regress bperwk_ wk if ptnum == `i'
	predict p
	replace p1=p if ptnum == `i'
	drop p
}

I'm pretty much a Stata novice. So, I apologize if I am missing something obvious. Using version 10.1.

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