Dear Aca,
assuming that you are interested in whether the means of the groups differ
rather than in difference in location of the distributions by group, why
don't perform bootstrap ANOVA test to allow for the skewed distribution of
the triglyceride level?
Kind Regards,
Carlo
PS As far as log transformation is concerned, the following reference may be
helpful: Manning WG, Mullahy J. ESTIMATING LOG MODELS: TO TRANSFORM OR NOT
TO TRANSFORM? NBER Technical Working Paper 246.
http://www.nber.org/papers/T0246
-----Messaggio originale-----
Da: [email protected]
[mailto:[email protected]] Per conto di Aca N.T.
Inviato: sabato 1 novembre 2008 12.12
A: [email protected]
Oggetto: Re: st: Kruskal-Wallis equivalent for survey data with pweight
Thanks Maarten & Steven, I have to change the analyses for LOS.
However, I've picked a wrong example here since I have some other
skewed variables for which KW test remains appropriate I think (eg.
triglyceride level). Can you suggest how to perform the analysis using
Stata?
Thanks in advance.
Aca
On Fri, Oct 31, 2008 at 4:24 PM, Maarten buis <[email protected]>
wrote:
> --- "Aca N.T." <[email protected]> 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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