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Re: st: Trouble producing population standard deviations with collapse (sd)


From   Austin Nichols <austinnichols@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Trouble producing population standard deviations with collapse (sd)
Date   Fri, 13 Jul 2012 23:35:31 -0400

Matt Vivier <mvivier@remedypartners.net>:
Also collapse the count N for each var, then multiply each SD by sqrt((N-1)/N)

On Fri, Jul 13, 2012 at 4:36 PM, Matt Vivier <mvivier@remedypartners.net> wrote:
> Hello all,
>
> My specs are:
> Stata/IC 12.1 for Windows (64-bit x86-64)
> Revision 06 Feb 2012
>
> I am having some trouble getting collapse to produce the result I am
> looking for. I have done some searching, and have not found anyone
> else presenting this problem. I need it to generate the population
> standard deviation for a large number of subsets of data, but it
> appears the command I am using is generating a sample standard
> deviation. Each subset of the data represents 100% of the population I
> am interested in the SD for. Is there a simple way to do this, or will
> I need to compute the SD using another process?
>
> My code is as follows:
>
> collapse (sum) TotCost TotAcute TotPostAcute ReadmissionCost
> ReadmissionClaims count (sd) SDTotCost=TotCost
> SDTotPostAcute=TotPostAcute SDReadmissionCost=ReadmissionCost (mean)
> AvgTotCost=TotCost AvgTotPostAcute=TotPostAcute
> AvgReadmissionCost=ReadmissionCost, by(drg_condition TriggerProvider
> year)
>
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