Markus
I think you may have specified your second group backwards
for the first group you have [1 1; 1 2] This says the scans correspond to
the first level of factor 2 (subject is ignored) and the first and second
levels of factor 2.
for the second group you have [2 1; 2 2]. This says you have one scan
corresponding to group 2 and one to group 1 both at the second level. Thus
you would have 3 conditions [1 1], [1 2] and [2 2].
Try instead for the second group [2 2; 2 1] (or better yet put them in order
[2 2; 1 2] and enter the scans in the appropriate order).
darren
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Darren Gitelman, MD
Department of Neurology
Northwestern University
voice: (312) 908-8614
fax: (312) 908-5073
page: (312) 695-1849
email: [log in to unmask]
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> -----Original Message-----
> From: SPM (Statistical Parametric Mapping)
> [mailto:[log in to unmask]] On Behalf Of Markus Burgmer
> Sent: Thursday, January 10, 2008 5:11 AM
> To: [log in to unmask]
> Subject: [SPM] problem with flexible factorial design setup
>
> dear list.
>
> i read the discussion in the list about the 2x2 ANOVA with
> great interest, because i like to setup a similiar design. so
> i followed the procedure of darren and matt for the flexible
> factorial design setup.
> i designed 3 factors (subject (2xn), group (2 groups), condition (2
> conditions) /independence yes, yes, no / variance equal,
> unequal, unequal).
> specified the design by subject. for each subject of my group
> 1 the condition matrix is [1 1;1 2], for each subject of my
> group 2 [2 1;2 2].
> There is a main effect of subject (factor number 1) and an
> interaction of group x condition (factor numbers 2 3).
> This produces a design very similiar to the ones of darren
> and matt. i got n columns for my n participants, each with 2
> rows. Now the difference and my problem:
> i got only 3 columns of group x condition instead of my
> expected 4. these are column 1 (group1 x condition2), column
> 2 (group1 x condition2), and column 3 (group2 x condition2).
> the lacking column (group2 x condition1) seems to be mixed
> into column 2 (see attached file).
>
> does anybody know what my mistake is?
>
> thanks markus
>
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