I have repeated measures data with 3 measurements for which the correlation between repeated measures is shown below. I use PROC MIXED and have /TYPE= in the REPEATED statement.
I tried different covariance structures but only the model with UN(1) converges. I was expecting that AR(1) would converge because I thought that would be a better fit based on the PROC CORR results. I appreciate it if I have your insight on this.
(I tried ARH(1), AR(1), UN, VC, CS, UNR, TOEP, CSH, TOEPH)
proc corr data=wide; var M1 M2 M3; run;
Pearson Correlation Coefficients Prob > |r| under H0: Rho=0 Number of Observations
M1
M2
M3
M1
1.00000 42167
0.85104 <.0001 41466
0.78900 <.0001 40845
M2
0.85104 <.0001 41466
1.00000 41923
0.81367 <.0001 41028
M3
0.78900 <.0001 40845
0.81367 <.0001 41028
1.00000 41446
Thank you!
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