BookmarkSubscribeRSS Feed
athomp06
Calcite | Level 5

Can anyone tell me what the following error means? 

 

WARNING: The R matrix depends on observation order within subjects. Omitting observations from
the analysis because of missing values can affect this matrix. Consider using a
classification effect in the RANDOM _RESIDUAL_ statement to determine ordering in the R
matrix.

 

I am attempting to run repeated measures on some data. The design was 20 animals blocked into light and heavy bodyweights, then assigned to 1 of 2 treatments withing each block. The animals had biopsies at 5 time points and gene expression was measured on 8 genes at each point. Attached is the SAS input as well as the output. I am not sure my denominator DF are correct and this may be associated with the error? Any help would be greatly appreciated.

1 REPLY 1
cici0017
SAS Employee

When you have missing observations on the RANDOM _RESIDUAL_ statement in GLIMMIX then the procedure generates the warning message. Considering change the RANDOM _RESIDUAL_ to -

 

Proc glimmix data = JessicaPCR;

Class ID TRT BLOCK DAY;

Model AMPK = TRT|DAY/ddfm = KR;

random intercept / subject=BLOCK;

random intercept / subject=ID*TRT;

random day /subject = ID*TRT type=arh(1) residual;

LSMEANS TRT|DAY/ pdiff lines;

nloptions tech=nrridg;

Run;

 

The above RANDOM statement should make note go away.

sas-innovate-2024.png

 

Time is running out to save with the early bird rate. Register by Friday, March 1 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
  • 2165 views
  • 1 like
  • 2 in conversation