# SDM calculations

## Mean analyses

This procedure calculates meta-analytic means, with their statistical significance based on Monte Carlo randomizations. You can specify a filter for subgroup analyses.

### To calculate a mean

Press the button [Mean]

*or*

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

### Command-line and batch usage

mean *filter*

*Example:*

MyMean = mean

### Log

The p = 0.005 thresholds (for positive and negative differences)
obtained after each randomization are saved in a text file called
*(name_of_the_mean)*_z.htm, e.g. MyMean_z.htm. This
is useful for studying the stability of the threshold.

### References

(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.
.

(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.
.