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Re: st: Test for trend in surveys


From   Philip Ryan <philip.ryan@adelaide.edu.au>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Test for trend in surveys
Date   Tue, 30 Sep 2008 20:09:35 +0930

Well, the z statistic testing the coefficient on the exposure variable is as
valid and as useful a summary (test) statistic as the chi-square statistic
produced by a test of trend in tables.  If you prefer chi-squares, you could
just square the z statistic to get the chi-square on 1 df.  And if you prefer
likelihood ratio chi-squares to the Wald z (or Wald chi-square) then the
modelling approach can deliver that also.

Phil

Quoting Ángel Rodríguez Laso <angelrlaso@gmail.com>:

> Thanks to Philip and Neil for their advice.
>
> Philip's proposal is absolutely compatible with survey data, but I was
> interested in a summary statistic of the type of Pearson chi-squared.
>
> To this respect, Neil puts forward a test (nptrend) that would be
> perfect if it allowed complex survey specifications. I believe strata
> and clusters are not important because the formula for the standard
> error of this nonparametric test (see Stata Reference Manual K-Q page
> 338) should not be affected by these specifications. But nptrend does
> not accept weights as an option, what I think makes it unsuitable for
> complex survey analyses.
>
> Angel Rodriguez Laso
>
> 2008/9/29 Philip Ryan <philip.ryan@adelaide.edu.au>:
> >
> > For a 2 x k table [with a k-category "exposure" variable] just set up a
> logistic
> > dose-response model:
> >
> > svyset <whatever>
> > svy: logistic <binary outcome var>  <exposure var>
> >
> > and check the coefficient of <exposure var>, along with its confidence
> interval
> > and P-value.
> >
> > If you prefer a risk metric rather than odds, then use svy: glm..... with
> > appropriate link and error specifications.
> >
> > Phil
> >
> >
> > Quoting Ángel Rodríguez Laso <angelrlaso@gmail.com>:
> >
> >> Dear Statalisters,
> >>
> >> Is there a way to carry out a test for trend in a two-way table in
> >> survey analysis in Stata?
> >>
> >> Many thanks.
> >>
> >> Angel Rodriguez Laso
> >> *
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> >>
> >
> >
> > --
> > Philip Ryan
> > Professor
> > Discipline of Public Health
> >
> > Director, Data Management and Analysis Centre
> > Associate Dean (IT)
> > Faculty of Health Sciences
> >
> > University of Adelaide
> > 5005 South Australia
> > AUSTRALIA
> > CRICOS Provider Number 00123M
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-- 
Philip Ryan
Professor
Discipline of Public Health

Director, Data Management and Analysis Centre
Associate Dean (IT)
Faculty of Health Sciences

University of Adelaide
5005 South Australia
AUSTRALIA
CRICOS Provider Number 00123M
-----------------------------------------------------------
This email message is intended only for the addressee(s)
and contains information that may be confidential and/or
copyright.  If you are not the intended recipient please
notify the sender by reply email and immediately delete
this email. Use, disclosure or reproduction of this email
by anyone other than the intended recipient(s) is strictly
prohibited. No representation is made that this email or
any attachments are free of viruses. Virus scanning is
recommended and is the responsibility of the recipient.
*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/



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