Hi everyone,   I tried to run proc mixed with several random effects, and used KR method to correct df.  In my study, I presented a set of stimuli (words) to each participant and varied two features of these stimuli. I've set up two random effects (subjects and stimuli), since the stimuli were in fact crossed with participants. In addition, the presentation order of stimuli for each participant was recorded and named 'trial'.    I've tried different ways to run this script, but the den df in the output did not seem to be corrected (den df = the number of trials * the number of subjects).  The code is attached below.  Your help is greatly appreciated! Thank you!   proc mixed data=dataset1 covtest noclprint namelen=100 ic method=ml; class subject targetword; model rt = condition|feature1|feature2 trial /ddfm=KR solution; random int trial / subject=subject Type=un; random int/ subject=targetword Type=un; run; ... View more