ERROR in proc PSMATCH: The support region does not exist.

[yahoo0806]

Hi all,

It's my first time to use PSMATCH procedure and when I feed my data in proc PSMATCH, no matter how I change my region statement, SAS keeps giving me the error message: The support region does not exist.

I'm wondering what I should check/what might go wrong? Based on this message, from where should I start checking? 

Below is the SAS code I am using:

proc psmatch data=all1 region=allobs;
class treatment;
psmodel treatment(Treated='1')=apoegr age sexcd stage cdrsbbl mmsebl adacogbl eduyrs med sympdur reg plasmaptau;
assess lps var=(apoegr age sexcd stage cdrsbbl mmsebl adacogbl eduyrs med sympdur reg plasmaptau) /
weight=atewgt plots=(boxplot barchart);
output out(obs=all)=out_iptw lps=_lps ps=_ps atewgt=_iptw;
run;

[MichaelL_SAS]

I believe the most likely reason for that error would be if there is no overlap in the predicted propensity scores between the two treatment conditions. I think that error will cause PROC PSMATCH to exit before creating the output data set you requested, so to see if there is any overlap in the predicted propensity scores you could try fitting the same model in PROC LOGISTIC and use an output data set it produces to see if there is any overlap between the treatment conditions.