Please have a look at this example: http://i.imgur.com/3KEReVZ.png
I want to compare 3 different models (left, middle, right) and two different groups (top, bottom).
The maps show unthresholded F-values ranging from 0 to >20.
However, I think the values cannot be compared, because for example the upper row has much less subjects, therefore the F-values are generally lower.
If I set the colormap limits from 0 to 40, the bottom row would look much nicer (not everything yellow as it is now) but not much would appear in the top row. Also the model of the F-map on the right has more parameters and therefore seems to have generally higher F-values.
Either I use separate colorbar limits for each map, which may seem like cheating, or apply some kind of normalization to F-values to account for different number of subjects and ANOVA levels...
Are there some references or guidelines? In all the papers I find, somehow miraculously the same colorbar and limits always match every map...
Thanks
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