Variances significantly different ? (independent samples)

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#673

From: Patrick Haggard
Date: Wed, 23 Dec 1992 11:43

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Hello.  There was a thread a while back about the Pitman procedure
for testing whether the variances of two related samples are
significantly different.  Could anyone fill me in on how to do the
equivalent for unrelated samples.  I have approx. 25 measurements in test
A, and approx. 25 measurements taken in test B.  The units of measurement
are the same in the two tests.  I want to see whether performance
is more variable on test A.
Hays' book ("Statistics"), and most other stats books,
just give the simple F test between the
two variances, but I seem to remember people being rather unhappy
about using that method when it was last discussed.  Can anyone
suggest any alternative test, please?
Thankyou
Patrick
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Patrick Haggard                         Email (WORLD): ph@physiol.ox.ac.uk
University Laboratory of Physiology     Email (JANET): ph@uk.ac.ox.physiol
Parks Road,                             Tel. (0865) 272116
Oxford, OX1 3PT                         Fax. (0865) 272469
England
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From: ph@physiology.oxford.ac.uk (Patrick Haggard)
Newsgroups: sci.math.stat
Subject: Variances significantly different ? (independent samples)
Message-ID: <1992Dec23.114358.7198@galen.physiol.ox.ac.uk>
Date: 23 Dec 92 11:43:58 GMT
Sender: ph@physiol.ox.ac.uk (Patrick Haggard)
Organization: Physiology Department, Oxford University, Oxford, UK.
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Originator: ph@galen.physiol