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r_1470
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@r_1470-4453
Last seen 9.6 years ago
Dear list,
having read the description of GeneSetTest I understand that it tests
whether a
specified subset of genes have higher values of a test statistic than
random
expectation, using a permutation test. If the test statistic has
positive and
negative values it is treated as 't-like'; if it has only positive
values it is
treated as 'F-like'.
My question is: is there any restriction on the type of statistic used
in this
analysis? If GeneSetTest employs a straightforward permutation test
then the
probability distribution of the statistic shouldn't matter, should it?
Only
whether it contains positive-only versus positive and negative values?
To give a couple of specific examples:
1) The deviance is a very useful statistic in generalized linear
modelling and
maximum likelihood analysis - would there be any issue with using the
deviance
as the test statistic?
2) Any number of other 'statistics' that are not probability
distributions
commonly employed in hypothesis testing might be calculated from gene
expression
data, a simple example being log fold change. Could such a measure
appropriately
be used in GeneSetTest (in the sense that it wouldn't violate any of
the
assumptions required to produce unbiased p values)?
Many thanks and best wishes
Richard.
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