## Getting Started Example for PROC PSMATCH

```/****************************************************************/
/*          S A S   S A M P L E   L I B R A R Y                 */
/*                                                              */
/*    NAME: PSMCHGS                                             */
/*   TITLE: Getting Started Example for PROC PSMATCH            */
/* PRODUCT: STAT                                                */
/*  SYSTEM: ALL                                                 */
/*    KEYS: Propensity score matching                           */
/*   PROCS: PSMATCH                                             */
/*    DATA:                                                     */
/*                                                              */
/* SUPPORT: Yang Yuan             UPDATE: Oct 17, 2016          */
/*     REF: PROC PSMATCH, GETTING STARTED EXAMPLE               */
/*    MISC:                                                     */
/****************************************************************/

data drug1;
do jorder=1 to 490;
if (ranuni(99) < .55) then Gender='Male  ';
else                       Gender='Female';

Age= 30 + 20*ranuni(99) + 3*rannor(9);
if (Age < 25) then  Age= 20 - (Age-25)/2;
Age= int(Age);

BMI= 20 + 6*ranuni(99) + 0.02*Age + rannor(9);
if (BMI < 18) then BMI= 18 - (BMI-18)/4;
BMI= int(BMI*100) / 100;

pscore= 4. - 0.35*Age + 0.35*BMI + 0.01*rannor(99);
if (Gender='Female') then pscore= pscore - 0.2;

id1= ranuni(99);
output;
end;
run;

proc sort data=drug1 out=drug2;
by pscore;
run;
proc rank data=drug2 out=drug3 descending;
var pscore;
ranks porder;
run;

data drug4;
set drug3;
if (porder < 100) then do;
if (ranuni(99) < .45) then Drug= 'Drug_X';
else                       Drug= 'Drug_A';
end;
else if (porder < 300) then do;
if (ranuni(99) < .30) then Drug= 'Drug_X';
else                       Drug= 'Drug_A';
end;
else if (porder < 450) then do;
if (ranuni(99) < .15) then Drug= 'Drug_X';
else                       Drug= 'Drug_A';
end;
else                          Drug= 'Drug_A';
run;

data drug5;
set drug4;
if (porder > 4);
run;

proc sort data=drug5;
by id1;
run;

data drug5;
set drug5;
PatientID= _n_;
run;

proc sort data=drug5 out=drugs (keep=PatientID Drug Gender Age BMI);
by jorder;
run;

proc print data=drugs(obs=10);
var PatientID Drug Gender Age BMI;
run;

ods graphics on;
proc psmatch data=drugs region=cs;
class Drug Gender;
psmodel Drug(Treated='Drug_X')= Gender Age BMI;
match method=optimal(k=1) exact=Gender distance=lps caliper=0.25;
assess lps allcov / weight=none plots=(barchart boxplot);
output out(obs=match)=Outgs lps=_Lps matchid=_MatchID;
run;

proc sort data=outgs out=outgs1;
by _MatchID;
run;

proc print data=outgs1(obs=10);
var PatientID Drug Gender Age BMI _PS_ _LPS _MatchWgt_ _MatchID;
run;

```