Dear Humphrey
Roughly speaking, a paired sample t-test helps remove unwanted variance, ie
variance in the pre-test scores. This would make the paired sample test more
powerful than the indeoendent samples test, so you may well find the paired
sample test giving significant results while the independent samples test
does not. Normally, you are not particularly interested in the pre-test
scores, you are interested in the effects of the treatment, so I would
personally always prefer paired in this situation.
Garry Gelade
-----Original Message-----
From: SPSSX(r) Discussion [mailto:
[hidden email]] On Behalf Of
Humphrey Paulie
Sent: 09 September 2008 20:34
To:
[hidden email]
Subject: paired vs independent samples t-test
Dear all,
in pre-test post-test studies where only one group in involved for comparing
the means before and after treatment "paired samples t-test" is required. is
that right?
i was just wondering how can independent samples t-test in such a situation
change the results. I mean is it possible to find a mean difference
significant with a pairde t-test and insinificant with an independent
t-test?
cheers
Humphrey
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