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Re: st: Weights


From   Steven Dubnoff <sdubnoff@circlesys.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Weights
Date   Thu, 01 May 2008 10:01:00 -0700

If I can weigh in on this, as someone who knows way too much about file format internals...

SPSS (on disk) compresses each data element. It is extremely efficient for typical survey data since each small signed integer goes into one byte. Everything else goes into doubles. Strings are stored in multiple fixed-length segments and not very efficiently at all.

If you run your data through Stat/Transfer into Stata format using our default optimization, you will end with a file that will be the same as one that has been compressed by Stata. This will occur outside of Stata, so you will ultimately be able to use larger datasets with a fixed amount of memory. You can also automatically drop variables which are entirely missing or constant, which is useful when you are creating subsets of rows for analysis.

Best,

Steve


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Steven Dubnoff sdubnoff@circlesys.com
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