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Re: st: Kruskal-Wallis equivalent for survey data with pweight


From   Steven Samuels <sjhsamuels@earthlink.net>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Kruskal-Wallis equivalent for survey data with pweight
Date   Fri, 31 Oct 2008 08:54:10 -0400

||

I don't believe that -sts test- is -svy- enabled, but -stcox- is. - stcox- is based on ranks of the observations and so is non-parametric in that way. With indicator-variables for groups, -stcox- will perform the equivalent of the log-rank test for equality of distributions, not the Kruskal-Wallis test. With -stcox- you can add interactions of group x time (or log(time). This makes it possible to test for crossing distribution curves.

-Steve
On Oct 31, 2008, at 5:24 AM, Maarten buis wrote:

--- "Aca N.T." <acant29@gmail.com> wrote:
I have a simple question about testing length of stay (LOS)
differences among 5 groups. The response variable (LOS) has a skewed
distribution. I have previously transformed the LOS (log
transformation) and tried parametric statistic (ANOVA using
svy:regress), but not happy when performing back-transformation for
SD/SE. I rarely used non-parametric statistics before even for
non-survey data, so really this issue is a hassle for me. I believe,
however, that Stata has a test equivalent to Kruskal-Wallis for
survey data.

The conventional way of analysing length of stay data is using survival
analysis. So I would -stset- the data, and than use -sts test- to do
the test. You can specify weights in the -stset- command. See:
-help stset- and -help -sts test-.

Hope this helps,
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 N515

+31 20 5986715

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



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