Something like this will put the character variables into a list suitable for use in a length statement in a data step The DSN1 and 2 must resolve to be in upper case, if they are in separate libraries than you need to modify the parameters to include both libraries, (lib1=, lib2= for example), make similar %upcase assignment, in the comparison (libname in ("&lib1","&lib2")) and the set statement, set &lib1..&dsn1 &lib2..&dsn2 ; Note the value for the comparison TYPE='char' , char must be lower case as that is how this is stored in the dictionary table. %macro stack (lib=, dsn1=, dsn2=, outset=); %let lib=%upcase(&lib); %let dsn1=%upcase(&dsn1); %let dsn2=%upcase(&dsn2); proc sql; /*   create table varlengths as*/    select string into :varlengths separated by ' '    from (    select catx(' $ ',name,MAX(length)) as string    from dictionary.columns    where libname="&LIB" and memname in ("&DSN1","&DSN2")       AND TYPE='char'    group by name)      ; QUIT; data &outset;      length &varlengths ;      set &lib..&dsn1            &lib..&dsn2; run; %mend; and to execute somethingl like: %stack (lib=work, dsn1=set1, dsn2=set2, outset=combinedset); ... View more

does the code make sense? its pretty simple, do you have any other suggestions? ... View more

Hi SAS'ter, What do you need? Sensitivity and Specificity are polygons running from (low,1) to (high,0) and from (low,0) to (high,1) resp. or vice versa when the measured data values range from low to high, and combined as ROC curve, forgetting the data values, from (0,0) to (1,1) where the x-axis is 1-specificity and the y-axis is sensitivity. So do you need confidence bands? Then I'm sorry I can't help you. Or do you rely to specific parameters like the AUC (Area Under roc Curve) or to the Youden index, the maximum of all possible (sensitivity + specificity -1) values or, you speaking of sensitivity values, just those sensitivity values from the Youden index? The values you mention, 0.87 and 0.89, could be all 3 of them. The first, since SAS9.2, can be done with PROC LOGISTIC and the ROC statement, the second and third one only, as far as I know, with bootstrap resamples of your data. Eventually this last task can be done with PROC SURVEYSELECT, but still I didn't apply that. Otherwise it's an easy task to create 1000 or 10000 resamples of your data and take the limits of the inner 95% of the values in question as the confidence limits Hope that helps a bit. Hans ... View more