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Re: st: Parameters returned by -lincom- after -logistic-


From   Roger Newson <roger.newson@kcl.ac.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Parameters returned by -lincom- after -logistic-
Date   Mon, 09 May 2005 12:34:45 +0100

Hello again (especially StataCorp)

One more query re using -lincom- after -svy- commands in Stata 8. How are the degrees of freedom calculated? I cannot find anything about this on Page 21 of -[SVY]-. I ask because a lot of the examples in -[SVY] lincom for svy- have t-statistics instead of z-statistics, and, as I understand it, the programs -svymean-, -svyratio- and -svytotal- use a method dependent on whether -e(complete)- is -complete- or -available-, with a vector degrees of freedom in the latter case and a scalar degrees of freedom in the former case.

Best wishes

Roger


At 19:05 08/05/2005, Richard Williams wrote:

At 06:48 PM 5/8/2005 +0100, Roger Newson wrote:
Thanks to Richard for warning us about this little quirk re -lincom- after -svy- commands in Stata 8. This is controlled by the undocumented Stata 8 command -is_svy-, which you can find out about by typing

whelp is_svy
Thanks Roger. It is there in Stata 9 as well (hopefully it works with the new svy prefix?):

http://www.stata.com/help.cgi?is_svy

I wonder if this new svy prefix approach will cause potential problems for old post-estimation commands, e.g. if you had a post-estimation command for -logit-, could it potentially have problems if you had run -logit- with the svy prefix? Or for that matter, with new programs, perhaps you need to check if svy has been used if that will affect how your program operates. I'll be glad when I get Stata 9 in a few weeks and can stop asking and just check these things out for myself.


-------------------------------------------
Richard Williams, Notre Dame Dept of Sociology
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--
Roger Newson
Lecturer in Medical Statistics
Department of Public Health Sciences
Division of Asthma, Allergy and Lung Biology
King's College London

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Opinions expressed are those of the author, not the institution.

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