Hi,

I have a question and I hope you can help me. I was able to run the SDM toolbox for my data on grey matter studies, which is cool.
Then I wanted to perform a meta-regression for disease severity (0-4 score). I think I should look at the file severity_z_0 to understand the association with this variable, right? Do negative values reflect a negative association (higher severity, lower grey matter?).
I noticed that SDM generates the blobs belonging to this analysis, so I used these files to extract the values for each study. For doing this I used the tab extract values and selected on of the blobs (e.g. mask_Severity_0_z_p_0.00500_1.000_10_neg_blob1). The results in firefox however show that for each study there is no value (NA). I also tried other blobs, but get the same output.
What am I doing wrong? Am I missing a step?
I would like to generate the scatter plots similar to the study:Voxel-wise meta-analysis of grey matter changes in obsessive–compulsive disorder (Radua).

Any help would be greatly appreciated!
Many thanks.
Best
Heidi

Dear Heidi,

severity_z_0 indicates the (fitted) abnormality in the least severe samples, severity_z_1 indicates the (fitted) abnormality in the most severe samples, and severity_z_1m0 indicates the difference between them (i.e. the association).

Blue clusters reflect a negative association.

Regarding the blobs, do you mean NA in the "Z" column? Don't worry about this, just use the "estimate" column. And if you want to make the dots in the scatter plot somehow proportional to the weight of each study, use the inverse of the values in the "variance" column.

Hope this helps,

Joaquim