Posted by
Ornelas, Fermin on
Mar 23, 2007; 11:52pm
URL: http://spssx-discussion.165.s1.nabble.com/Levene-test-with-large-sample-tp1074661p1074664.html
I think you should report the F-test. Having said that, if you are
concerned with the test results; you should also rely on the traditional
plots of your residuals against the predictors and the fitted response
variable. If the plots show the typical pattern of non constant
variances then the data validates the results of the test. But if these
plots contradict the test results you may want to also add a comment to
your results.
I am coming to the conclusion that the plots tell the story better.
Another possibility for test results to contradict your plots could be
an improper model specification or omission of an important predictor.
Fermin Ornelas, Ph.D.
Management Analyst III, AZ DES
Tel: (602) 542-5639
E-mail:
[hidden email]
-----Original Message-----
From: SPSSX(r) Discussion [mailto:
[hidden email]] On Behalf Of
Stephen Salbod
Sent: Friday, March 23, 2007 3:04 PM
To:
[hidden email]
Subject: Levene test with large sample
Good Evening Everyone,
I hope someone will guide me around this simple problem that fell in
front
of me today.
Which t test do I want to report?
I have two groups:
Group1 n= 1,512 M=2.5668 SD1=.80339
Group2 n= 273 M=2.3187 SD2=.96877
Levene's Test for Equality of Variance F= 27.531, p<.0001.
1) Equal Variances Assumed t(1783) = 4.542, p <.001.
2) Equal Variances NOT Assumed t(342.79) = 3.991.
The large N has created a statistically significance difference out of a
trivial difference; furthermore, the variances between the groups are
statistically different.
Can Levene's result be ignored because of the large sample or is it
recommended that I report t test #2?
I would appreciate any suggestions and, if possible, references on this
problem.
I thank you in advance.
Stephen Salbod, Pace University
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