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Re: st: Weights


From   "Austin Nichols" <austinnichols@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Weights
Date   Wed, 30 Apr 2008 11:53:02 -0400

Can you put a 8GB memory stick on the computer--can't Vista treat
those as RAM?  How did you turn your 2.4 GB .csv file into a 5.5GB
Stata file, anyway?  Can you specify a different variable type in that
process, or save different sets of variables to different files (with
an identifier for later merging)?

On Wed, Apr 30, 2008 at 11:41 AM, Martin Weiss
<martin.weiss@uni-tuebingen.de> wrote:
> Austin,
>
> if only I could open the file and compress it... I have the latest gear in
> terms of hard- and software (MP/2 10.0 64 bit, 4GB RAM, Vista Business 64
> bit, ...) but it is next to impossible to open the 5.5 GB file. Virtual mem
> makes things so slow it takes all the fun out of it... So I am stuck in a
> bit of a quandary.
>
> Martin Weiss
> _________________________________________________________________
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>
>
> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Austin Nichols
> Sent: Wednesday, April 30, 2008 5:27 PM
> To: statalist@hsphsun2.harvard.edu
> Subject: Re: st: Weights
>
> Martin Weiss <martin.weiss@uni-tuebingen.de>
>
> SPSS is using the wrong type of weight, and therefore will give you
> incorrect standard errors.  See -help weights- and -help svy- and the
> manuals for more.
>
> Perhaps the large size of the Stata file is due to all variables being
> stored as doubles?  Try -compress- on an extract and see -help
> datatypes-.
>
> Note that -mean- restricts to obs where all vars are nonmissing, so
> instead of e.g.
>
> ds, has(type numeric)
> loc num `r(varlist)'
> mean `num'
>
> try
>
> ds, has(type numeric)
> loc num `r(varlist)'
> foreach v of loc num {
>  mean `v'
> }
>
> or just use -summarize- with aweights or pweights
> (pweights=aweights+_robust so point estimates are identical, but
> variance estimates differ).
>
> On Wed, Apr 30, 2008 at 10:57 AM, Martin Weiss
> <martin.weiss@uni-tuebingen.de> wrote:
> > Dear Statalisters,
> >
> > can anybody give me a clue as to the array of weighting options in Stata?
> I
> > have an important project where I would really like to make headway...
> >
> > My dataset features a size of 2.4 GB as .csv. When I translate this into
> > SPSS, it ends up with 2.7 GB while the equivalent Stata dataset has 5.5 GB
> > (!). Anyway, I usually pick out the interesting variables beforehand
> because
> > Stata is unable to open the entire dataset. The first column of the data
> > contains samplingweights. The dataprovider ships a pdf with the
> descriptives
> > for the marginal distributions of the variables in the population so I
> know
> > the true values.
> >
> > Now here lies the rub: when I weight -summarize- with analytic weights,
> the
> > approximately correct mean and standard deviation pop out. When I let
> Stata
> > estimate the mean with the -mean- command, with analytic weights attached
> in
> > the same fashion, I get widely differing results for the point estimate of
> > the mean, far from the true values. In SPSS, I simply go to -weight cases-
> > and everything comes out correct.
> >
> > Do I have to -svyset- the data? When I try to -frequency weight- the data,
> > Stata complains that non-integers are not allowed while SPSS seems to not
> > quarrel with them. Why is it that SPSS needs one command at the beginning
> of
> > the session while Stata has a (differing) tab dedicated to weighting for
> > every single command?
> >
>
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