From Mathieu.DAcremont at pse.unige.ch  Thu Feb 22 17:59:18 2007
From: Mathieu.DAcremont at pse.unige.ch (Mathieu.DAcremont at pse.unige.ch)
Date: Thu, 22 Feb 2007 17:59:18 +0100 (CET)
Subject: [Rd] Error in ICC1.CI ? (PR#9528)
Message-ID: <20070222165918.C2C495ACE5@slim.kubism.ku.dk>


Hello,

I'm using the function ICC1.CI of the psychometric package. I wonder if 
there is an error in this function. Because in the paper of McGraw and 
Wong (Psychol Met, 1, 30) or the one of Shrout & Fleiss (Psychol Bult, 
86, 420), the Ftab is not calculate in the same manner of the lower and 
upper bound.

According to these articles Ftab for the lower bound is:

F(df.row, df.error)

and for the upper bound, it is:

F(df.error, df.row).

So the df are reversed. However, in your function ICC1.CI, the Ftab is 
calculated in the same way for the upper and lower bound:

     Ftab <- qf(noma/2, df1, df2, lower.tail = F)
     Fl <- Fobs/Ftab
     Fu <- Fobs * Ftab
     lcl <- (Fl - 1)/(Fl + n)
     ucl <- (Fu - 1)/(Fu + n)

Is that an error ?

Best regards,

-- 
Mathieu d'Acremont, PhD		Mathieu.Dacremont at pse.unige.ch
Ma?tre-Assistant               	tel/fax +4122 379 98 20/44

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[Rd] Error in ICC1.CI ? (PR#9528)
Mathieu.DAcremont at pse.unige.ch