A colleague and I are performing logistic regressions. He's using SAS and
I'm using SPSS. I've been able to match up all my SPSS output with his SAS output, except that the SAS output contains a table that shows the Sensitivity, Specificity, % False Negative and % False Positive for each probability level. Is it possible to generate this table in SPSS? I've looked at the documentation for LOGISTIC REGRESSION and don't see an option that will do it. Alternatively, is it available as part of another analysis? TIA, Pat |
Hi Pat
If you are using multiple logistic regression, then you have to save the predicted values as a new variable and then, as someone else has suggested, run ROC analysis. You will get sensitivity and false positive rate. False negative rate and specificity can be easily obtained by substraction. The following example computes sensitivity & 1-specificity (=false positive rate) for a simple logistic regression model, but the process is similar for multiple regression models: * Dataset from Hosmer&Lemeshow's Applied Logistic Regression *. DATA LIST FREE/ age chd (2 F8.0). BEGIN DATA 20 0 23 0 24 0 25 0 25 1 26 0 26 0 28 0 28 0 29 0 30 0 30 0 30 0 30 0 30 0 30 1 32 0 32 0 33 0 33 0 34 0 34 0 34 1 34 0 34 0 35 0 35 0 36 0 36 1 36 0 37 0 37 1 37 0 38 0 38 0 39 0 39 1 40 0 40 1 41 0 41 0 42 0 42 0 42 0 42 1 43 0 43 0 43 1 44 0 44 0 44 1 44 1 45 0 45 1 46 0 46 1 47 0 47 0 47 1 48 0 48 1 48 1 49 0 49 0 49 1 50 0 50 1 51 0 52 0 52 1 53 1 53 1 54 1 55 0 55 1 55 1 56 1 56 1 56 1 57 0 57 0 57 1 57 1 57 1 57 1 58 0 58 1 58 1 59 1 59 1 60 0 60 1 61 1 62 1 62 1 63 1 64 0 64 1 65 1 69 1 END DATA. VAR LABELS age 'Age at follow-up start' /chd 'Coronary Heart Disease'. VALUE LABELS chd 0 'Absent' 1 'Present'. LOGISTIC REGRESSION chd /METHOD = ENTER age /SAVE = PRED (predict). ROC predict BY chd (1) /PLOT = CURVE /PRINT = SE /CRITERIA = CUTOFF(INCLUDE) TESTPOS(LARGE) DISTRIBUTION(FREE) CI(95) /MISSING = EXCLUDE . PC> A colleague and I are performing logistic regressions. He's using SAS and PC> I'm using SPSS. PC> I've been able to match up all my SPSS output with his SAS output, except PC> that the SAS output contains a table that shows the Sensitivity, PC> Specificity, % False Negative and % False Positive for each probability PC> level. Is it possible to generate this table in SPSS? I've looked at the PC> documentation for LOGISTIC REGRESSION and don't see an option that will do PC> it. Alternatively, is it available as part of another analysis? ----- Regards, Dr. Marta García-Granero,PhD mailto:[hidden email] Statistician --- "It is unwise to use a statistical procedure whose use one does not understand. SPSS syntax guide cannot supply this knowledge, and it is certainly no substitute for the basic understanding of statistics and statistical thinking that is essential for the wise choice of methods and the correct interpretation of their results". (Adapted from WinPepi manual - I'm sure Joe Abrahmson will not mind) |
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