Hi,
Back with a question about analyzing the repeated novelty data (read below for details). We've
decided to pair the runs that have the same stimuli (so, the Nov1 run with it's matched Nov2 run).
This means that in addition to doing a straight forward first (run), second (subject), and third
(group) level analysis I will also be doing a second level paired t-test of the Nov1 copes vs the
Nov2 copes within subject, then a third (subject) and fourth (group) level for these copes.
My question is this -- when you do the higher level analysis, do you take the number of tests into
account for significance of the maps? If so, how do I adjust this for the fact that I'm doing a set of
contrasts outside the normal analysis chain?
Thanks.
Robin
On Fri, 2 Apr 2004 16:46:53 -0500, Robin Goldman <[log in to unmask]> wrote:
>Hi there,
>
>New day, new question. We're running an event related novelty oddball
>study. (Give people a task, surprise them every now and then with a
>"novelty" event (Nov1) that is always something new, after a while, in
>another run, repeat some of these novelty events (Nov2) to see what
>happens). We scan the subjects over multiple runs (12). All of these
>contain Nov1 events, all but the first contain Nov2 events. (None of
>the novelty events are repeated in the same run, only in later ones).
>
>So here's the question. It seems to me there are a number of ways to
>analyze this data to see if there is a difference between first time
>and repeated novel events (Nov1 vs Nov2).
>
>1. In all but the first run (where there are no Nov2), model an EV that
>gives some relationship between the Nov1 and Nov2 events. But I don't
>want to a priori do this.
>
>2. Have one EV for Nov1 and one EV for Nov2, do a contrast within each
>run (all but run 1) of Nov1 vs Nov2. Then do a second level within
>subject of this cope, then a third level across subjects.
>
>3. Have one EV for Nov1 and one EV for Nov2. Do a contrast for each EV.
>Do a second level analysis within subject of the Nov1 contrast and also
>the Nov2 contrast (so, 12 copes for Nov1 and 11 for Nov2). Do a third
>level within subject of the Nov1 cope vs the Nov2 cope. Then a fourth
>across subjects. (As I'm writing this, I'm sure this is not the way to
>go...)
>
>So perhaps I answered my own question... thoughts?
>
>thanks again.
>Robin
>
>________________________
>Robin Goldman, Ph.D.
>Hatch Center for MR Research
>Columbia University
>710 W. 168th Street, NIB-1
>New York, NY 10032
>(212) 342-0867
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