I have a group of about 1300 patients who had had disease 1 (subgroup 1), disease 2 (subgroup 2), or disease 3 (subgroup 3).

I have correlated certain biomarkers with their kidney function in the whole group (N=1300), and then in each of these subgroups (N = circa 400 in each subgroup)

e.g. Fibrinogen & GFR


I would like to work out if there is a statistical difference for these correlations across the 3 disease subgroups (R1 vs R2 vs R3). Is there a way to do this with STATA or SPSS

The only online calculators that I've found for fisher's z transformation only seem to allow comparison between two correlation coefficients (as opposed to 3 which is what I need).

I've also found this link: http://home.ubalt.edu/ntsbarsh/busin.../MultiCorr.htm but I'm not sure if this calculator is accurate?

Does anyone have any suggestions?

Dearbhla