Hello. I am using the decoding toolbox (TDT) with SPM12. I did a decoding analysis where I got both res_decision_values" and “signed_decision_values” as the output. I assumed that “res_decision_values” would only provide decision values that are greater than 0 (positive). However this doesn’t seem to be the case. I also looked at what the sign is coding for and unfortunately it looks arbitrary.
In the analysis I did, both predicted and true values can take on values {0,1}. Just skimming over the decision value, predicted label, and the true label shows that there is no clear cut relationship between the sign of the decision value
dVal pred. true
" 23 -0.010038 0 1
25 0.0047602 0 0
27 0.0022084 0 1
29 0.0073449 0 0
31 0.020894 1 1
47 0.019534 0 1
49 -0.010381 0 0 "
Any guidance is appreciated!