Date:         Wed, 21 May 2008 00:27:44 +0100
Reply-To:     Angshu Bhowmik <angshub@hotmail.com>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
Comments:     RFC822 error: <W> MESSAGE-ID field duplicated. Last occurrence
              was retained.
From:         Angshu Bhowmik <angshub@hotmail.com>
Subject:      comparing groups before and after treatment
In-Reply-To:  <200703250400.l2OAkOac031468@mailgw.cc.uga.edu>
Content-Type: text/plain; charset="us-ascii"

Hello everyone,

I wonder if anyone could advise me (a clinical doctor with no statistical
training) about the correct way to test whether people have improved in 8
variables (e.g. how far they can walk, blood oxygen levels, spirometry, etc)
after an exercise program. I think they have, and the patients love it, but
I need to formally confirm it in order to keep the service running.

If I understand correctly, simply doing paired t-tests or Wilcoxon's tests
on each variable is not correct because multiple comparisons make it more
likely that something will show up. Is doing multiple t-tests and changing
the desired p value to 0.05 / 8 i.e. 0.00625 the only way to do this?

Many thanks for your kind help

Angshu

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