The
so-called “exact tests” in SPSS Exact Tests are an implementation
of the permutation test approach to obtaining the tail area of a distribution. Many
conventional approaches rely in a law of large numbers. For example, the
computed Pearson chi-square or Likelihood ratio chi-square in Crosstabs follow
the chi-square distribution as sample size gets large. In the case of small
samples, heavily tied data, or extreme imbalance, the computed statistic may
not follow the claimed distribution. There is a technical literature published
by Mehta, Patel, and colleagues that develops the algorithms found in SPSS
Exact Tests. Some citations are at http://www.cytel.com/Learn/Publications.aspx.
Book
citations include “Exact Analysis of Discrete Data” by Karim F. Hirji
(publisher: Chapman and Hall/CRC), and Phillip Good’s “Permutation,
Parametric, and Bootstrap Tests of Hypotheses” published by Springer.
Tony
Babinec
[hidden email]
"They always say time changes things,
but you actually have to change them yourself." Andy Warhol
From: SPSSX(r)
Discussion [mailto:[hidden email]] On
Behalf Of Staffan Lindberg
Sent: Sunday, June 21, 2009 7:59
AM
To: [hidden email]
Subject: Reference to the
procedure "Exact test" in the module Exact Tests
Dear
list!
I’m
at a loss how to reference the use of the procedure “Exact test” in
the module Exact Tests in SPSS. Usually you refer to a significance test
by the developer (i.e Student’s t-test, Pearson Chi-square etc). Here I
am confused about what the correct name of the test is, as Exact test both is
the name of the module and a procedure within the module. Is there a reference
about this test (within the module)? Is this some development of
Fischer’s exact z-test for 2*2 tables applying to larger tables?
best
Staffan
Lindberg
Sweden
Locked
