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Re: st: svy: proportions vs svy: tab


From   "Lawrence Hanser" <lhanser@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: svy: proportions vs svy: tab
Date   Fri, 21 Dec 2007 11:17:24 -0800

You are correct, this is implausible.  One of my programmers was using
a svy: tab command and taking the cell proportions to calculate row
proportions.  The other was using the svy: proportion command to get
the row proportions directly.  The rounding error in converting cell
proportions to row proportions accounted for the difference...

When I looked more closely at what they had done, I suggested that
they should have used the "row" option in the svy: tab command to
obtain row proportions instead of taking cell proportions and manually
calculating row proportions (doh!).

On Dec 21, 2007 10:03 AM, Austin Nichols <austinnichols@gmail.com> wrote:
> Lawrence Hanser <lhanser@gmail.com>:
> That seems implausible.  Can you provide commands and output?  Can you
> duplicate the problem on a publicly available dataset, e.g. by
> starting with
>  webuse nhanes2
> ?
>
> On Dec 21, 2007 12:07 PM, Lawrence Hanser <lhanser@gmail.com> wrote:
> > Dear Colleagues:
> >
> > We're getting slightly different estimates (up to .04) using the svy:
> > proportions command vs. the svy: tab command (weighted with p
> > weights).  Does anyone know why?  Is one of these methods more
> > accurate for computing weighted proportions?
>
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