Dear experts,
My experiment was 2*3 mixed design, with group (3 levels) as a between-group factor, and session (2 levels, pre- and post-intervention) as a within-group factor. I used the flexible factorial module in SPM8 to explore the main effects of session and the group*session interaction. Since insula was a region of interest based on previous studies, I selected the insula from AAL atlas and generated a mask using PickAtlas. I then selected this mask in Explicit Mask option in factorial design specification to do the ROI analysis. However, errors occurred in model estimation step, and the detailed information was in attached figure 1 and 2. I am really appreciated if anyone could help me solve this problem.
Thank you in advance.
Yuan-Wei
Hi Ioana,
Thank you very much for your helpful comments.
I have check the preprocessing carefully, and I am confident there is no problem.
I don't think it is due to a lack of power either, since the data of more than 60 subjects were included in the analysis, and every group had at least 15 subjects.
In fact, I am a little confused about the statement that "there were no significant voxels". Because I have also tried ACC mask instead, although there is no significant voxel after FWE correction, Matlab did not report any errors.
Best,
Yuan-Wei
Hi Ioana,
Your explanation seems reasonable, but I have reviewed ACC results, in which 1 voxel remained at uncorrected 0.001 in the contrast for the main effect of session, whereas no voxel remained at uncorrected 0.05 in the contrast for the interaction.
I have also tried manual operation step by step, and I found that Matlab crashed in model estimation. If it is related to the type of contrast or criteria of correction, Matlab should crash in contrast manager or results report, right?
Best,
Yuan-Wei
Hi Ioana,
Thank you for your very helpful comments!
I will check again if there was any problems in data analysis. If not, there may be something wrong in the experiment design or hypotheses generating.
Thank you again for your reply.
Best,
Yuan-Wei
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