@RobertWF1 wrote:
For example, if I want to conduct greedy nearest neighbor propensity score matching where 1 to 5 control records may be matched to each treatment record, is specifying K=5 sufficient or will SAS attempt to match exactly 5 controls to each treatment?
The KMAX= option doesn't appear to be available for the greedy matching method.
Hello,
I have never done this, but as I read the documentation :
SAS/STAT® 15.2 User's Guide The PSMATCH Procedure
https://go.documentation.sas.com/doc/en/statug/15.2/statug_psmatch_syntax08.htm#statug.psmatch.methodopt
METHOD=FULL (KMAX=kmax <full-options>) KMAX=kmax >> specifies the maximum number of control units to be matched with each treated unit, where kmax >= 1.
METHOD=GREEDY <(K=k ORDER=order-option)>
K=k specifies the number of matching control units, where k > 0, for each treated unit. PROC PSMATCH performs k separate loops of matching for treated units. In each loop, the nearest control unit is sequentially matched to each treated unit. By default, K=1 (one control unit for each treated unit). AS I READ THIS , IT WILL MATCH EXACTLY K CONTROL UNITS TO EACH TREATED UNIT.
Example 100.4 Greedy Nearest Neighbor Matching https://go.documentation.sas.com/doc/en/statug/15.2/statug_psmatch_examples04.htm
Best,
Koen
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