topic Re: "Invalid reference value" error for PROC CAUSALMED in Statistical Procedures

"Invalid reference value" error for PROC CAUSALMED

dbcrow — Thu, 04 Sep 2025 07:21:41 GMT

Hi, folks-

When I run this PROC CAUSALMED with a CLASS statement and reference values

proc causalmed data=data.climate23 decomp pmedmod poutcomemod;
	class healthharm_rc (ref="No") trans (ref="Cisgender");
	model healthharm_rc = housing_instab | trans;
	mediator housing_instab = trans;
	format healthharm_rc yesno_alt. trans trans. housing_instab housing_instab.; 
run;

I get this error:

ERROR: Invalid reference value for trans.
ERROR: No valid observations due to invalid or missing values in the outcome, mediator, treatment, explanatory, weight, or frequency variable.

The really weird thing is that when I use the same CLASS statement in PROC LOGISTIC, the code produces no errors:

proc logistic data=data.climate23;
	class healthharm_rc (ref="No") trans (ref="Cisgender");
	model healthharm_rc = housing_instab | trans;
	format healthharm_rc yesno_alt. trans trans. housing_instab housing_instab.; 
run;

Even weirder, the above PROC CAUSALMED code was working just fine as recently as two weeks ago. I know that a workaround is (ref=FIRST), but it's really bugging me that code which worked so recently now doesn't. Also, it seems a surer bet to spell out the reference category rather than risk getting the SAS internal category order wrong--for example, (ref=LAST) would run but produce wrong results.

Version info. is:

- Base SAS: 9.4_M8

- EGP: 8.4 Update 2

- SAS/STAT: 15.3

Based on what I've read in five other posts in the support forums, here's what I've done so far in an attempt to fix the error:

1) Checked formats to ensure that the spellings are the same in PROC FORMAT and the reference value in the CLASS statement; that there aren't any leading or trailing blanks, etc.

proc format;
	value yesno_alt		0='No'
				1='Yes'
				.='Missing';

	value trans		0='Cisgender'
				1='Transgender';

	value housing_instab	0 = 'Very Stable'
				1 = 'Fairly Stable'
				2 = 'Somewhat Stable'
				3 = 'Fairly Unstable'
				4 = 'Very Unstable';
run;

2) Run PROC CONTENTS to see if that the above formats were properly attached to the corresponding variables. They are.

3) Reset the SAS session and restarted SAS.

Here's some sample data and code that reproduces the error:

proc format;
	value yesno_alt		0='No'
				1='Yes'
				.='Missing';

	value trans		0='Cisgender'
				1='Transgender';
run;

data person;
   infile datalines delimiter=','; 
   input healthharm_rc trans mediator;
   datalines;                      
0,1,3
0,1,4
1,0,3
1,0,3
1,1,2
0,0,2
1,1,1
0,1,1
0,0,1
1,1,4
;

proc logistic data=person;
	class healthharm_rc (ref="No") trans (ref="Cisgender");
	model healthharm_rc(event="Yes") = trans;
	format healthharm_rc yesno_alt. trans trans.;
run; 

proc causalmed data=data.climate23;
	class healthharm_rc (ref="No") trans (ref="Cisgender");
	model healthharm_rc = housing_instab | trans;
	mediator housing_instab = trans;
	format healthharm_rc yesno_alt. trans trans. housing_instab housing_instab.; 
run;

Any ideas?

Thanks,

David

Re: "Invalid reference value" error for PROC CAUSALMED

SAS_Rob — Thu, 04 Sep 2025 13:59:03 GMT

This appears to be a defect of some sort. I would suggest that you contact Technical Support directly so they can investigate the issue.

Re: "Invalid reference value" error for PROC CAUSALMED

dbcrow — Thu, 04 Sep 2025 22:10:26 GMT

Have done so. I'll let you know the outcome.

Re: "Invalid reference value" error for PROC CAUSALMED

mm3215 — Wed, 24 Sep 2025 17:19:58 GMT

Running into this same issue and wondering you have received an answer? Thanks in advance!

Re: "Invalid reference value" error for PROC CAUSALMED

SAS_Rob — Wed, 24 Sep 2025 17:26:06 GMT

This is a defect that is documented, along with a work-around, in the KB article linked below:

SAS Support - The CAUSALMED procedure incorrectly issues "ERROR: Invalid reference value" when you specify the REF= option

Re: "Invalid reference value" error for PROC CAUSALMED

dbcrow — Wed, 24 Sep 2025 18:55:56 GMT

Hi, SAS_Rob-

Thanks. From the posting dates, it looks like this issue might have become documented because of my original post (which also suggested one of the workarounds)! 🙂

Any idea if the SAS Team is going to fix the underlying issue? The workarounds work, but, for the reasons I pointed out, aren't optimal.

Many thanks,

David

Re: "Invalid reference value" error for PROC CAUSALMED

SAS_Rob — Thu, 25 Sep 2025 13:34:31 GMT

Yes, this should be fixed in the next release of SAS, although the timetable for its release is not set as of yet.