BookmarkSubscribeRSS Feed
RobertWF2
Fluorite | Level 6

I've been running proc psmatch for an analysis, using 1:1 nearest neighbor matching on propensity scores calculated from proc logistic.

 

I did not include the WEIGHT=ATT option in the ASSESS statement to my code.

 

Are the matching results still valid? Which weighting scheme is proc psmatch using as a default? I do see in the output dataset of matched records _MATCHWGT_=1 for every record.

 

proc psmatch data=logistic_output;
  	class class age gender;
  	psdata ps=ps  treatvar=class(treated='Treatment');
	match method=greedy(k=1) exact=(age gender) caliper=0.25;
   	output out(obs=match)=psm_results;
run;
1 REPLY 1
RobertWF2
Fluorite | Level 6

Ah hold on - if I add an ASSESS / WEIGHT=ATTWGT; statement to my proc psmatch code I see the following message after running.

 

WARNING: WEIGHT=ATEWGT and WEIGHT=ATTWGT are not allowed if a MATCH statement is specified. WEIGHT=MATCHWGT is used.

Ok so looks like weights can't be used for 1:1 nearest neighbor matching?

 

Am I still estimating ATT when I run a proc ttest on the matched output data even if WEIGHT=ATT wasn't used?

sas-innovate-2024.png

📢

ANNOUNCEMENT

The early bird rate has been extended! Register by March 18 for just $695 - $100 off the standard rate.

 

Check out the agenda and get ready for a jam-packed event featuring workshops, super demos, breakout sessions, roundtables, inspiring keynotes and incredible networking events. 

 

Register now!

What is Bayesian Analysis?

Learn the difference between classical and Bayesian statistical approaches and see a few PROC examples to perform Bayesian analysis in this video.

Find more tutorials on the SAS Users YouTube channel.

Click image to register for webinarClick image to register for webinar

Classroom Training Available!

Select SAS Training centers are offering in-person courses. View upcoming courses for:

View all other training opportunities.

Discussion stats
  • 1 reply
  • 294 views
  • 0 likes
  • 1 in conversation