Dear all,
I have a question about t- contrasts. I fear that this might
be a little naive, but........
Say, I have a condition A with 20 scans and a condition B
with 40
scan ( because B was scanned twice within the session).
When modelling the data, can I model A and B as one
regressor each , or should B modelled as 2 regressors?
In other words, should the contrast between A and B be
1 -1 or
2 -1 -1 ( I understand that this model will allow me to ask
more questions, but that particulr question is not something
that I am interested in..)
Is there a difference in the power of the contrasts?
Do these contrasts answer the same question mathematically?
Thank you very much.
\Priyantha.
--
Priyantha Herath, MBBS
Division of Human Brain Research, tel: +46 (0)8 728 7298
Department of Neuroscience, +46 (0)8 728 7297
Karolinska Institute,
S 171 77 Stockholm, fax: +46 8 309045
Sweden.
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