From: Newson, Roger B <[email protected]>
Subject: RE: st: adjusted Mann-Whitney/Wilcoxon test
To: "'[email protected]'" <[email protected]>
Date: Thursday, April 9, 2009, 3:39 PM
As David said, the -somersd- package, downloadable from SSC,
can estimate stratified versions of rank parameters. The
user has a choice of parameters, which may be Kendall's
tau-a, Somers' D, or a Theil-Sen median slope. All of
these parameters are available in stratified versions,
restricted to comparisons within strata defined by a
categorical variable. And the -somersd- package has 3 .pdf
manuals, which the user can download with the package, in
which the methods and formulas are explained.
I hope this helps.
Best wishes
Roger
Roger B Newson BSc MSc DPhil
Lecturer in Medical Statistics
Respiratory Epidemiology and Public Health Group
National Heart and Lung Institute
Imperial College London
Royal Brompton Campus
Room 33, Emmanuel Kaye Building
1B Manresa Road
London SW3 6LR
UNITED KINGDOM
Tel: +44 (0)20 7352 8121 ext 3381
Fax: +44 (0)20 7351 8322
Email: [email protected]
Web page: http://www.imperial.ac.uk/nhli/r.newson/
Departmental Web page:
http://www1.imperial.ac.uk/medicine/about/divisions/nhli/respiration/popgenetics/reph/
Opinions expressed are those of the author, not of the
institution.
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of
David Airey
Sent: 09 April 2009 18:23
To: [email protected]
Subject: Re: st: adjusted Mann-Whitney/Wilcoxon test
To me, stratified generally means controlling for a
non-continuous
covariate.
-Somersd- provides rank-based statistics for group
comparisons
allowing for strata.
-Dave
On Apr 9, 2009, at 10:45 AM, Constantine Daskalakis wrote:
> I have the same question as Ricardo.
>
> By stratified, we mean controlling for another
covariate:
>
> Wilcoxon of Y by X, controlling for Z
>
> StatXact does this stratified Wilcoxon.
>
>
> David, the parallel is Mantel-Haenszel for dichotomous
outcome.
>
> So, the command would look something like this:
>
> ranksum y x, by(z)
>
> or
>
> ranksum y, by(x) strata(z)
>
>
> On 4/9/2009 10:44 AM, David Airey wrote:
>> .
>> If ttest generalizes to regress, then ranksum
generalizes to what?
>> There is a lot of literature on ranksum tests with
clustered data
>> if that's what you mean. Maybe you can define
your data more
>> precisely...
>> On Apr 9, 2009, at 8:44 AM, Ricardo Ovaldia wrote:
>>>
>>> Dear all,
>>>
>>> Is there a way to adjust the -ranksum- test
for covariates? Or is
>>> there another way to do an adjusted
Mann-Whitney U test? Something
>>> similar to relationsip between ttest and
regress.
>>>
>>> Thank you,
>>> Ricardo.
>>>
>>> Ricardo Ovaldia, MS
>>> Statistician
>>> Oklahoma City, OK
>
>
>
> --
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> Constantine Daskalakis, ScD
> Associate Professor,
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> 1015 Chestnut St., Suite M100, Philadelphia, PA
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>
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