BookmarkSubscribeRSS Feed
stodo53
Obsidian | Level 7

Hi all,

 

I am running a mixed linear model using "PROC MIXED" procedure in SAS and it includes an interaction term. I am just having difficulty understanding the two reference groups, and what exactly they are a reference for. Would someone be able to help me interpret this? Ultimately, I would like to model the following "Compared to males (or females) on TAC, males (or females) on TAC have a higher/lower lvmi". Thanks in advance!

 

Current model:

	MODEL lvmi_chinali=	yearsincetx  ageattx TAC syssds_04 bmisds_r egfr_schwartz TAC*sex / SOLUTION CL;

Results:

stodo53_0-1725524363890.png

 

4 REPLIES 4
stodo53
Obsidian | Level 7

I read over this many times, and although I think I understand it, I don't really see how this could be made interpretable in laymans terms. When I add both the main effects and the interaction term, it becomes more confusing to me how to interpret this since there is only one estimate produced for the interaction.

 

	MODEL lvmi_chinali=	yearsincetx  ageattx TAC sex syssds_04 bmisds_r egfr_schwartz TAC*sex / SOLUTION CL;	

stodo53_0-1725533739910.png

 

Ksharp
Super User

" since there is only one estimate produced for the interaction."
That was supposed to be , since in design matrix SEX='Male' is 1 and TAC='1' is 1 ,and only when SEX='Male' and TAC='1' it should be ,others are zero.
You'd better post it at Stat Forum:
https://communities.sas.com/t5/Statistical-Procedures/bd-p/statistical_procedures
And Calling @StatDave  @SteveDenham @lvm

Ksharp
Super User

Check @Rick_SAS blog:
https://blogs.sas.com/content/iml/2019/12/03/longitudinal-data-response-profile-model.html

 

According to Rick's blog:
sex=Male and TAC=1 is 1.0446 less than sex=Male and TAC=0

sas-innovate-white.png

Missed SAS Innovate in Orlando?

Catch the best of SAS Innovate 2025 — anytime, anywhere. Stream powerful keynotes, real-world demos, and game-changing insights from the world’s leading data and AI minds.

 

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.

SAS Training: Just a Click Away

 Ready to level-up your skills? Choose your own adventure.

Browse our catalog!

Discussion stats
  • 4 replies
  • 1089 views
  • 0 likes
  • 2 in conversation