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Re: st: Missing cases after contract with large weight


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Missing cases after contract with large weight
Date   Thu, 20 Dec 2007 22:05:01 +0000 (GMT)

--- Friedrich Huebler <fhuebler@gmail.com> wrote:
> I discovered that -contract- drops observations when a weight with
> large numbers is used. What is the explanation for this and is
> -contract- designed to work this way?

You ran into a numerical precision problem: _freq is stored as a long
variable, and can thus not store numbers larger than 2,147,483,620. If
-contract- results in numbers larger than that, they will turned into
missings. In general storing these numbers as long seems good practice
to me, but in these cases you might want to be able to revert to
storing them as float or double. 

-- Maarten

-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands

visiting address:
Buitenveldertselaan 3 (Metropolitan), room Z434

+31 20 5986715

http://home.fsw.vu.nl/m.buis/
-----------------------------------------


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