When you have a requirement like "before" you may need to provide more criteria. Below is an example of providing data in the form of data steps and one approach to a comparison.   data work.a; informat patientid $5. testdate1 - testdate3 date9.; format testdate1 - testdate3 date9.; input patientid testdate1 - testdate3; datalines; 1 01JAN2011 03MAY2012 04JUN2014 ; run; data work.b; informat patientid $5. presciptiondate date9.; format presciptiondate date9.; input patientid presciptiondate; datalines; 1 01JAN2010 1 05MAY2013 1 25JUL2013 ; run; /* single date per record may work better*/ proc transpose data=work.a out=work.atrans prefix=testdate; by patientid; var testdate1 - testdate3; run; proc sql; create table work.example as select a.patientid, a.testdate1 as testdate, b.presciptiondate from work.atrans as a inner join work.b as b on a.patientid=b.patientid where a.testdate1 < b.presciptiondate ; quit; As you can see in the work.example data set there are multiple testdates before a given prescriptiondate.     I named the test date variables testdate1 through testdate3 to take advantage of short hand variable name use that would not be possible with names like test1date test2date and so one. For instance to change the code I wrote to read data set A with 20 variables you only need to change the 3 to 20 in three places. To use test1date through test20date you would have list them explicitly.   The transpose step gets one record per patient id and test date so the search comparison done in proc sql only needs to look at one variable. Otherwise you would have to compare 20 test date variables to each prescription date and you might have to do more work to identify which test date was the "before" value in the result. Proc SQL has many different ways to test comparisons and make results based on values of variables in multiple sets. The example is only one.   If you only wanted to know which prescription dates had at least one prior test then something like this: proc sql; create table work.example2 as select distinct a.patientid, b.presciptiondate from work.atrans as a inner join work.b as b on a.patientid=b.patientid where a.testdate1 < b.presciptiondate ; quit; ... View more

It is not clear what problem you are having. Is it that you don't know how to use a regression procedure to come up with the predicted values? Is it the reference lines? Is it overlaying the observations and the predicted values?   Here are two approaches. The first uses only the REG statement in PROC SGPLOT. This performs OLS regression. The second uses PROC GLM to output predicted values for each group. The predicted values are then overlaid on the data. You can substitute another regression procedure for GLM.   data a; call streaminit(1); group = 1; do t = 0 to 52; y = 90 + 5/52*t + rand("normal"); output; end; group = 2; do t = 53 to 156; y = 90 - 5/52*(t-53) + rand("normal"); output; end; group = 3; do t = 157 to 190; y = 20 + 25/52*(t-157) + rand("normal"); output; end; run; proc sgplot data=A; reg x=t y=y / group=group; refline 52 156 / axis=x; run; proc glm data=A plots=none; by group; model y = t; output out=modelOut predicted=pred; quit; proc sgplot data=modelOut; scatter x=t y=y / group=group; series x=t y=pred / group=group break lineattrs=(thickness=2); refline 52 156 / axis=x; run; If this does not answer your question, please provide the SAS code that you are using and describe how you want to modify the output. ... View more

Hi again,    So inorder to put this formate within the data , I 've created a nother date variable and      date=servdate; format date yymon7.; run; so it gave me this format within the same data.    Thanks again Lamia ... View more