topic Re: Clinical analysis: PROC PSMATCH (SAS/STAT or SAS/OR) results differ between SAS 9.4 and Viya in Statistical Procedures

Clinical analysis: PROC PSMATCH (SAS/STAT or SAS/OR) results differ between SAS 9.4 and Viya

Stephanvd — Wed, 05 Aug 2026 09:32:16 GMT

We are migrating an existing analysis from SAS 9.4 to SAS Viya. The user requirement is that results are reproduced 1-to-1 (clinical analysis).

The PS matching procedure does not reproduce exactly:

The estimated propensity scores differ slightly (small numerical differences)
In several cases the assigned Match ID differs

I have attached a small test program. It is not the original code, but it does reproduce the differences.

My questions
1. Are others seeing comparable differences in the output of SAS/STAT or SAS/OR procedures when migrating to Viya?
2. How would you deal with such differences in a migration of clinical analyses to Viya, what do you consider acceptable, and how do you document or justify it?

Any experience or guidance is very welcome.

Appendix 1: psmatch_test_anon.sas
Appendix 2: compare between output test code, SAS PC (9.04.01M8, WX64) vs SAS Viya (V.04.00M0, LIN X64)

Re: Clinical analysis: PROC PSMATCH (SAS/STAT or SAS/OR) results differ between SAS 9.4 and Viya

sbxkoenk — Mon, 10 Aug 2026 21:49:18 GMT

So you notice very small discrepancies between PSMATCH statistical results in SAS 9.4 on PC (Microsoft) and SAS Viya 4 on a Unix/Linux server.

These discrepancies - if any - usually stem from hardware-level floating-point arithmetic differences. Or do you have any indication that there’s more to it than that?

See these links:

When you compare output datasets with PROC COMPARE,

try METHOD=relative Criterion=0.000000001; for example
or look at the fuzz option

BR,

Koen

Re: Clinical analysis: PROC PSMATCH (SAS/STAT or SAS/OR) results differ between SAS 9.4 and Viya

JuanS_OCS — Tue, 11 Aug 2026 15:07:17 GMT

Hi @sbxkoenk, Koen, indeed.

How do you manage what is on an acceptable level within a clinical trial analysis? Do you have any experience around it?

Thanks in advance!
Best regards, Juan

Re: Clinical analysis: PROC PSMATCH (SAS/STAT or SAS/OR) results differ between SAS 9.4 and Viya

sbxkoenk — Tue, 25 Aug 2026 11:35:23 GMT

Hello Juan,

I was seeking to find out whether there are any FDA and/or EMA regulatory guidelines around this topic, but I couldn't find any (maybe my investigation was too superficial !).

I also checked the CAMIS project (https://psiaims.github.io/CAMIS/) because it deals with discrepancies and conflicting results in (pharma) statistical analyses between different statistical software packages. I was hoping to find some FDA/EMA statements there on how to handle tiny differences, but that's not the case.

BR,
Koen