|Date: ||Wed, 30 Oct 2002 13:43:40 -0800|
|Reply-To: ||Dale McLerran <stringplayer_2@YAHOO.COM>|
|Sender: ||"SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>|
|From: ||Dale McLerran <stringplayer_2@YAHOO.COM>|
|Subject: ||Re: advice wanted on statistical test|
|Content-Type: ||text/plain; charset=us-ascii|
I don't believe that Mantel-Haenszel is appropriate for either
of the tests that the original correspondent wanted to address.
By way of recall, the problem was one in which a response
measured at two time points (pre- and post-treatment) was
obtained on case and control subjects. Thus, we have correlated
responses. The correspondent wanted to test whether there was a
difference between pre- and post-treatment responses within each
of the case/control groups. McNemar's test is appropriate for
the test of association when the responses are correlated as they
are when examining the response vs pre-/post-treatment by group.
The second test that the correspondent wanted to make was to see if
the change between pre- and post-treatment responses was different
for cases and controls. This might be where a Mantel-Haenszel
statistic comes into play. We do now have a third (stratification)
factor to consider. But Mantel-Haenszel is used to examine whether
there is an association between X and Y across all strata defined
by Z. That is not what is wanted for this third test. Moreover,
Mantel-Haenszel does not allow for correlated responses. The
Breslow-Day test is used to examine whether the odds ratio is
homogeneous across strata. So, one might consider that statistic
rather than the Mantel-Haenszel statistic. However, to the best
of my knowledge, Breslow-Day does not allow for correlated
responses, either. Thus, I firmly believe that the second
question "Is the change from pre-test to post-test different
between case and control?" can only be examined through a model
which takes into account the correlated responses. GEE and a
generalized linear mixed model are two such methods.
--- "David L. Cassell" <Cassell.David@EPAMAIL.EPA.GOV> wrote:
> "Dennis G. Fisher" <dfisher@CSULB.EDU> replied:
> > I am not sure if a Mantel Hansel approach would work for you or
> That's Mantel-Haenszel, also known as Cochran-Mantel-Haenszel,
> although some people make a distinction based on the test. Often,
> the 1-degree-of-freedom correlation test is called the
> test, while the 'ANOVA' statistic and the 'general association'
> statistic (together with the first-mentioned test) are often
> collectively called Cochran-Mantel-Haenszel tests.
> PROC FREQ does all three CMH tests (when appropriate). And
> yes, I agree with you that this approach may be reasonable.
> However, Dale's suggestion may provide more power. I don't know
> of a reference off the top of my head which would provide a
> recommendation either way...
> David Cassell, CSC
> Senior computing specialist
> mathematical statistician
Fred Hutchinson Cancer Research Center
Ph: (206) 667-2926
Fax: (206) 667-5977
Do you Yahoo!?
HotJobs - Search new jobs daily now