Intraclass Correlation for Continuous Outcome Variable using PROC MIXED:

http://mchp-appserv.cpe.umanitoba.ca/Upload/SAS/Intraclass_Correlation_Coefficient.sas.txt

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Example 3:
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proc mixed data=<Input Data>;

class famnum famsize mar_1stbirth mom_1stbirth_under20 male order;

model la_index = famsize mar_1stbirth mom_1stbirth_under20 male order;

random famnum;

run;

NOTE 1: Intraclass correlation cannot be computed for binary outcome variables using PROC MIXED.

NOTE 2: Intraclass correlation has to be computed manually using PROC MIXED.

Formula: ICC = Var1 /(Var1 + Var2)

NOTE 3: The ICC denotes the variability accounted for by the �between-cluster� factor with respect to

the overall variability, or in other words, it denotes the degree of homogeneity within clusters.

NOTE 4: When using PROC MIXED and there are many clusters (levels or groups in the RANDOM variable), this can be problematic for SAS can run out of memory.