SDM calculations

Family-wise error correction

The family-wise error correction is attained by running a subject-base permutation test and obtaining a distribution of the maximum statistic. This distribution is then used to threshold the meta-analysis images obtained in the Mean or Linear Model calculations, resulting in a corrected p-values map.

To calculate a FWE

Press the button [FWE]

or

Select [FWE] in the Statistics menu, to open the following dialog:

Multi-threading

The calculation of the distribution step of the FWE calculation, which will take long in any meta-analysis, can be run in parallel using concurrent threads. Note: is not advisable to use more concurrent threads than the available in your pc. You can learn the number of available threads in your pc at the 'multithreading' tab of the preferences windows.

Command-line and batch usage

perm number_of_permutations,model_name where the model_name is the name of a model for which a Mean or Linear Model has previously been calculated.

Example:

perm 1000,model_name

Note: In order to modify the number of concurrent threads while using the command-line, you need to modify by hand the value of nthreads in the section (xml tag ) corresponding to the desired model in the file sdmpsi_params.xml, that is created after the Mean or Linear Model is calculated.

References

(current method): Albajes-Eizagirre A, Solanes A, Vieta E and Radua J. Voxel-based meta-analysis via permutation of subject images (PSI): Theory and implementation for SDM. NeuroImage 2019; 186:174.

Winkler A M, Ridgway GR, Webster MA, Smith SM and Nichols TE. Permutation inference for the general linear model. Neuroimage 2014; 92:381-397.