Documentation Example 3 for PROC PSMATCH
/****************************************************************/
/* S A S S A M P L E L I B R A R Y */
/* */
/* NAME: PSMCHEX3 */
/* TITLE: Documentation Example 3 for PROC PSMATCH */
/* PRODUCT: STAT */
/* SYSTEM: ALL */
/* KEYS: Propensity score matching */
/* PROCS: PSMATCH */
/* DATA: */
/* */
/* SUPPORT: Yang Yuan UPDATE: Oct 17, 2016 */
/* REF: PROC PSMATCH, EXAMPLE 3 */
/* 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;
ods graphics on;
proc psmatch data=drugs region=treated(extend(distance=ps mult=one)=0.025);
class Drug Gender;
psmodel Drug(Treated='Drug_X')= Gender Age BMI;
match distance=ps method=varratio(kmin=1 kmax=4) exact=(Gender) caliper=.;
assess ps var=(Gender Age BMI)
/ stddev=pooled(allobs=no) nmatchmost=5
plots(orient=vertical nodetails);
id BMI;
output out(obs=match)=OutEx3 matchid=_MatchID;
run;
proc sort data=OutEx3 out=OutEx3a;
by _MatchID;
run;
proc print data=OutEx3a(obs=10);
var PatientID Drug Gender Age BMI _PS_ _MATCHWGT_ _MatchID;
run;