FSL pundits,
Using the same patient and control groups, FA data was analyzed initially using TBSS then subsequently examined using the tbss_sym FA script. The design and contrast files were identical, and the number of permutations was identical (5000). With an alpha level of .90 (0.10) between group differences (p <0.10, corrected) occurred in both analyses: in the TBSS results the expert or trained group showed greater left FA than controls in several structures; the tyss_sym analysis showed leftward FA of experts in some structures and hence relative rightward FA in the same structures in controls.
This suggests that left hemisphere dominance in experts is a contributing factor of outcomes for both tests, and FA results of the tests may be correlated. Is this a valid inference?
At .95 (0.05), only the tbss_sym FA test showed a surviving cluster (bilateral difference) that differed between the groups. Just considering the two FA tests, could it be inferred that the tbss_sym FA script is more sensitive? Or would it be more accurate to say that the bilateral difference (tbss_sym) is more pronounced than the absolute difference (TBSS)?
Any feedback would be much appreciated. Thank you
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