LLN, le 29/06/06
Dear Caroline,
If having your 5 conditions in the same run is not too difficult to
manage for your participants, than option A is probably the safer as
it will allow you to compare directly any pair of conditions. (Note
however that, for the same durantion, you will have less volumes per
condition per run.)
The "problem" with option B is that it is not recommended to compare
directly 2 conditions from 2 different runs (in your example cond B
from scan 1 and cond C from scan 2). Now, if each cond has its own
baseline in its run and you only want to compare differences between
runs (e.g., B-E and C-E), or if you never plan to compare 2
conditions from different runs, then option B should be OK.
I've already used the two options for different studies, and both
turned out to be fine.
Hope this helps,
Mauro.
>Dear SPMers,
>
>I have a very basic design questions.
>
>If I have 5 conditions (3 motions, 2 diff baseline) (A, B, C, D,
>E) for my study question, what is the best way to design the
>paradigm?
>
>Option A:
>5 conditions in one EPI scan, 20 sec each block, repeat 3 times in
>one scan = total scanning time 5 min
>and do repeat measurement
>
>scan1: A B C D E, A B C D E, A B C D E
>scan2: same as above
>scan2: same as above
>
>or
>
>Option B: 3 different EPI scans, and each scan with different motion
>condition.
>scan 1: A B E, A B E, A B E, A B E, A B E
>scan 2: A C E, A C E, A C E, A C E, A C E
>scan 3: A D E, A D E, A D E, A D E, A D E
>
>Thanks in advance
>
>best regards
>caroline
>
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Mauro PESENTI
Research Associate, National Fund for Scientific Research (Belgium)
Unite de Neurosciences Cognitives
Departement de Psychologie
Universite Catholique de Louvain
Place Cardinal Mercier, 10
B-1348 Louvain-la-Neuve
tel.: +32 (0)10 47 88 22
fax: +32 (0)10 47 37 74
E-mail: [log in to unmask]
http://www.nesc.ucl.ac.be
http://www.nesc.ucl.ac.be/mp/pesentiHomepage.htm
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