Michael Erb wrote:
> Dear Rik,
> what is the theoretical and practical difference between
> the "effects of interest" F-contrast in the form
> [ 1 0 0, 0 1 0, 0 0 1] and a single F-contrast entered as
> [ 1 1 1 ] ?
> Michael.
The [1 1 1] contrast tests whether the sum of squares of the
three parameter estimates explains significant additional variance
(in the reduced F-test); the [1 0 0; 0 1 0; 0 0 1] contrast tests
whether any of the squared parameter estimates explain
significant additional variance. In geometric terms, the former
tests for significant variance (in either direction) along the
vector [1 1 1]; the latter tests for significant variance along
any one of the component (axis) directions.
Rik
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DR R HENSON EMAIL [log in to unmask]
Wellcome Department of
Cognitive Neurology TEL (work1) +44 171 833 7483
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