On Thu, 16 Dec 2004 09:43:47 -0000, Rik Henson <[log in to unmask]> wrote:
>Mirta -
>
>Simply create T-contrasts for [1 0 -1 0] (canonical: before - after) and
[0 1 0 -1]
>(derivative: before - after) and enter the resulting contrast images into
a (two-way)
>ANOVA (no constant term; no within subject effects), and evaluate the F-
contrast
>for the effects of interest.
Rik,
Should one do the sphericity correction, a la "Random Effects Analyses
with Multiple Basis Functions Per Subject" (Henson and Penny)?
>
>Rik
>
>
>----- Original Message -----
>From: "Mirta Villarreal" <[log in to unmask]>
>To: <[log in to unmask]>
>Sent: Wednesday, December 15, 2004 7:08 PM
>Subject: [SPM] 2nd level analysis with F test?
>
>
>Hi all
>
>I want to perform a pair-t-test within a group of subjects before and
after some
>treatment. The problem is that for the individual analysis I get better
results when I see
>at the [1 0, 0 1] F contrast (model = hrf + first derivative).
>In previous e-mails I was recomend to evaluate the T-contrasts [1 0] and
[0 1] at the
>individual level first and take them to an ANova model. I did it and it
was ok.
>
>But how can I take this two contrast for each group to a pair t-test? I
should choose 4
>pairs? (pair 1= hrf before tretment, pair 2= TD before, pair 3= hrf
after, pair 4= TD
>after) or I can use directly the [1 0, 0 1] F contrast and 2 pairs?
>
>I apreciate any clue!
>Thanks
>
>Mirta
>
>
>
>
>Mirta Villarreal, PhD
>Neuroimage Laboratory
>FLENI
>Montaņeses 2325 (C1428AQK)
>Buenos Aires, Argentina
>C1428AQK
>Argentina
>Phone: 54 11 57773200 ext: 2925
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