Dear experts,
I have more basic questions regarding the practical application of featquery.
In my study I compare 2 age groups at 2 time points (before after training)
in two memory task conditions (low difficulty vs high difficulty).
I found Time x Group x Condition interactions in the whole –head analysis.
In order to examine the direction of the effects, I would like to extract
the parameter estimates to be able to analyze the changes in BOLD activation
in SPSS and to plot the % signal change.
I read the information about Featquery on the FSL homepage and understand
the basic steps. However, I still have some questions.
• Which parameters is one actually using for the statistical analysis in
SPSS and can one just extract them from the featquery output or does one
need to transform the data somehow?
• How is % signal change actually calculated – is that typically averaged
across voxels in a specific region or does one report the max values and if
so why?
• Is it possible to run the featquery for the higher-level FEAT directory
(averaged across individuals) and is there a difference if I would run it
for each individual at a lower level and then average across individuals.
• FSLView also provides one with the option to display % signal change – is
this actually comparable to the featquery results?
• Can you provide me with a good reference that could illustrate a good
hands-on example of using featquery to compare groups.
Thanks a lot for your help
Yvonne
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