Hi Alfonso,
Thank you for posting the CONN version of your SPM cross-validation scripts. The scripts work very nicely, but I have a few questions and could use some guidance on reporting the LOOCV output.
1) Are the values stored in the CV_DATA variable the GLM prediction errors after leaving out a given subject, or are they correlations between PE estimated using the full dataset vs. the LOOCV data set?
2) Would running a t-test against zero on the CV_DATA be the correct way to validate a cluster extracted from a seed-to-voxel analysis?
3) If a t-test were used and the cluster of interest was extracted from a between-groups contrast, a statistically significant t-test would be interpreted as positive evidence of validity. If the cluster was extracted from a single group or condition however, a null rather than significant finding would be considered positive evidence. Is this correct?
Thanks,
Jennifer
Thank you for posting the CONN version of your SPM cross-validation scripts. The scripts work very nicely, but I have a few questions and could use some guidance on reporting the LOOCV output.
1) Are the values stored in the CV_DATA variable the GLM prediction errors after leaving out a given subject, or are they correlations between PE estimated using the full dataset vs. the LOOCV data set?
2) Would running a t-test against zero on the CV_DATA be the correct way to validate a cluster extracted from a seed-to-voxel analysis?
3) If a t-test were used and the cluster of interest was extracted from a between-groups contrast, a statistically significant t-test would be interpreted as positive evidence of validity. If the cluster was extracted from a single group or condition however, a null rather than significant finding would be considered positive evidence. Is this correct?
Thanks,
Jennifer