# How to convert fwe_pvalue from fixel space into voxel space?

Hello @jdtournier ,
I am using [ fixel2voxel fwe_pvalue_fixel_space mean pvalue_voxel_space ] command to convert fwe_pvalue from fixel space into voxel space. However, the p-values are stored in 1-pvalue format in fixel space, and we lower threshold to 0.95.

My question is: how can I threshold pvalue in voxel space? I am using 0.05 as the threshold for statistical significant right now.

Many Thanks,
Suren

Hi @suren,

I don’t think there’s a single answer here, it depends on what you’re trying to do, and why.

• If you’re after the p-value of the least significant fixel, you can use:

``````fixel2voxel fwe_1mpvalue.mif min pvalue_voxel_space.mif
``````
• If you’re after the p-value of the most significant fixel, you can use the same command with the `max` operation

• if you’re after the number of significant fixels in that voxel, you could use (assuming a p<0.05 threshold for significance):

``````mrthreshold fwe_1mpvalue.mif -abs 0.95 - | fixel2voxel - sum num_sig_fixels_in_voxel.mif
``````
• if you just want to know whether any fixels where significant in each voxel, you could use the same as above, but additionally threshold the output:

``````mrthreshold fwe_1mpvalue.mif -abs 0.95 - | fixel2voxel - sum - | mrthreshold - -abs 1 any_sig_fixels_in_voxel.mif
``````

There are probably other combinations that may also make sense depending on exactly what you’re after.

But this all depends on why you would need to do this?

Cheers,
Donald.