Hi Guys! Hope someone could help me. Am performing binary logistic regression in SAS and am trying to figure out if it is possible to manually compute (via Excel) for the predicted probabilities (individual, cross validated, and cumulative) generated by SAS? If yes, what is the formula? I am using the formula exp(bo+(b1*x1)+...+(bn*xn))/(1+exp(bo+(b1*x1)+...+(bn*xn))) but the values don't match with the predicted probabilities. I've used sample from the SAS documentation and added the predicted probabilities (predprobs) in output. Data Neuralgia; input Treatment $ Sex $ Age Duration Pain $ @@; datalines; P F 68 1 No B M 74 16 No P F 67 30 No P M 66 26 Yes B F 67 28 No B F 77 16 No A F 71 12 No B F 72 50 No B F 76 9 Yes A M 71 17 Yes A F 63 27 No A F 69 18 Yes B F 66 12 No A M 62 42 No P F 64 1 Yes A F 64 17 No P M 74 4 No A F 72 25 No P M 70 1 Yes B M 66 19 No B M 59 29 No A F 64 30 No A M 70 28 No A M 69 1 No B F 78 1 No P M 83 1 Yes B F 69 42 No B M 75 30 Yes P M 77 29 Yes P F 79 20 Yes A M 70 12 No A F 69 12 No B F 65 14 No B M 70 1 No B M 67 23 No A M 76 25 Yes P M 78 12 Yes B M 77 1 Yes B F 69 24 No P M 66 4 Yes P F 65 29 No P M 60 26 Yes A M 78 15 Yes B M 75 21 Yes A F 67 11 No P F 72 27 No P F 70 13 Yes A M 75 6 Yes B F 65 7 No P F 68 27 Yes P M 68 11 Yes P M 67 17 Yes B M 70 22 No A M 65 15 No P F 67 1 Yes A M 67 10 No P F 72 11 Yes A F 74 1 No B M 80 21 Yes A F 69 3 No ; run; proc logistic data=Neuralgia; class Treatment Sex; model Pain= Treatment Sex Treatment*Sex Age Duration / selection=backward expb; run; proc logistic data=Neuralgia; class Treatment Sex; model Pain= Treatment Sex Age/expb ctable; output predprobs=(INDIVIDUAL CUMULATIVE CROSSVALIDATE); run; proc print data=data1;
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