SDM   Seed-based d Mapping
formerly "Signed Differential Mapping"
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SDM calculations

Mean analyses

This procedure calculates meta-analytic means. You can specify a filter for subgroup analyses, and up to two covariates (four if you're using the command-line).

To calculate a mean

Press the button [Mean]


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

Mean dialog


The MLE step of the mean calculation, which can take long in large meta-analyses, 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

mi number_of_imputations,model,filter where the model is the list of covariates to use separated by the character +.


model_name = mi 50,YBOCS,adults

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 file sdmpsi_params.xml, that is created after the preprocessing.


(original algorithms): Radua J and Mataix-Cols D. Voxel-wise meta-analysis of grey matter changes in obsessive-compulsive disorder. Br J Psychiatry 2009; 195:393-402. link .

(effect-sizes and variances): Radua J, Mataix-Cols D, Phillips ML, El-Hage W, Kronhaus DM, Cardoner N and Surguladze S. A new meta-analytic method for neuroimaging studies that combines reported peak coordinates and statistical parametric maps. Eur Psychiatry 2012; 27:605–611. link .

(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. link