```Date: Thu, 18 Dec 2008 06:31:29 -0500 Reply-To: Jim Groeneveld Sender: "SAS(r) Discussion" From: Jim Groeneveld Subject: Intraclass Correlation alternatives Hi friends, I am searching for ways to calculate the Intraclass Correlation and found the SAS macro IntraCC.sas of Robert M. Hamer. The macro produces 6 types of ICCs, based on Shrout & Fleiss (and 2 comparable ones based on Winer). The 6 types can briefly be described and discriminated as: Estimating the reliability of: a single rating the mean of several ratings --------------------------------- --------------- ---------------------- ----- * Raters for each subject are selected at random 1 4 * The same raters rate each case. These are a random sample. 2 5 * The same raters rate each case. These are the only raters. 3 6 More info can be found in the following urls: http://ourworld.compuserve.com/homepages/jsuebersax/icc.htm http://support.sas.com/kb/25/031.html http://www.nyu.edu/its/statistics/Docs/intracls.html We have the following design: a limited number of raters (say 5) judge 16 subjects on a single characteristic (or more independent ones) twice. I determine the ICC per rater using the above macro based on his two judgments of the 16 subjects. This is the rater's ICC between his (pairs of) judgments. I do this for each rater separately. It represents within rater reliability / agreement. I determine the overall ICC based on the average judgment of each pair of judgments of a subject per rater. This is the ICC between raters. It represents between rater reliability / agreement. My question is which of the 6 ICCs I have to regard applicable for both cases. My guess is nr. 3 for the first case and nr. 6 for the second one. Do you agree? An additional question is how to test these correlations for significance. Can you point me to documents with formulas and/or SAS code? I didn't find anything (yet). Regards - Jim. -- Jim Groeneveld, Netherlands Statistician, SAS consultant home.hccnet.nl/jim.groeneveld ```

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