LLN, le 17/10/08
Dear Mariska,
For behavioral results, the Anova is generally not much affected by
the inequality of groups. For functional results, I'm not sure it's
the case. Personally, I wouldn't trust too much a difference stemming
from unequal groups, but I guess a small inequality should be OK if
you have large groups (e.g., more than 15 participants). With small
groups (< 15), adding/dropping 2-3 participants can significantly
affect your RFX analyses.
Hope this helps,
Mauro.
>Hi Mauro,
>
>
>thanks for your reply!
>
>One more question:
>Do I need to have an equal amount of males/females in both
>experiments or doesn't it matter if the groups don't differ too much?
>
>
>greetings,
>Mariska
>PS This is a statistically valid method?
>
>
>
>2008/10/15 PESENTI Mauro
><<mailto:[log in to unmask]>[log in to unmask]>
>
>LLN, le 15/10/08
>
>Dear Mariska,
>
>Here is what I suggest:
>
>(1) Compute your contrast of interest at the first level for each
>subject individually,
>
>(2) port the corresponding con_* files to 2-level analyses using:
>
>- 1-sample t-tests with a contrast set at [1] for each group separately;
>
>- 2-sample t-tests to compare your two groups. Select all your con_*
>files for one groupe (say females), then all your con_* files for
>the other group (say males); set your contrasts depending on what
>you're looking at: ([1 -1] gives group 1 > group 2, [-1 1] gives
>group 2 > group 1).
>
>Hope this helps,
>
>Mauro
>
>.
>
>Hi all,
>
>
>Does anybody know how I can compare males vs females on one contrast
>from two experiments with different subjects (containing both males
>and females)?
>
>
>Greetings,
>Mariska
>
>
>
>--
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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
>
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>fax: +32 (0)10 47 37 74
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_____________________________________
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_____________________________________
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Just click your mouse and sponsors of The Hunger Site donate a
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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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