Dear El¿bieta,
One of the main reasons to use SPM for some data is that one can do
correction for multiple comparisons using random field theory.
However, that only makes sense if your data can be seen as samples
from a continuous random field. In what you describe there is no
continuity in any of the dimensions. The frequency dimension could
potentially be continuous but you discretised it into 5 bands. So you
can account for multiple comparisons in your data by either doing
bonferroni correction or using voxel-wise FDR. This could be done in
SPM but I'm not really sure SPM is the best software in this case as
it was designed for images and your data is not an image. You would
have to write some custom code to make sense of the results. In any
case you would either have to use a function that takes the data as
input such as spm_ancova or you should save your data as .nii images,
probably 18 x 18 x 5 and then you'll have 14 images per subject. But
again the way SPM presents the results wouldn't make sense for these
data as it assumes continuity.
Best,
Vladimir
On Fri, Jun 22, 2012 at 9:30 AM, El¿bieta Olejarczyk
<[log in to unmask]> wrote:
> Dear all,
>
> Can somebody advise me how resolve this statistical problem?
>
> I have the following data:
>
> 20 subjects * 14 experimental conditions * 324 flows (equivalent to one set
> of 18x18 roi_to-roi) * 5 frequency bands
>
> I would like to find the answer on the following questions:
> 1. which flows are significant for every of the experimental condition;
> 2. what is the frequency band for these flows.
>
> The amount of the data is too big to perform an analysis of variance.
>
> Could it be possible to treat every set of 18x18 as one map? In such a way,
> the problem would be reduced to test the following number of maps:
>
> 20 subjects * 14 conditions * 5 bands
>
> If this approach is possible, which SPM procedures should be applied and
> what format of data should be used?
>
> Otherwise, what statistical method would be appropriate to resolve this
> problem?
>
>
> Best regards,
> Elzbieta Olejarczyk
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