RE: BOV

From: "Kowalski, Ken" Ken.Kowalski@pfizer.com Subject: RE: [NMusers] BOV Date: Wed, September 22, 2004 7:51 am Nick, In the two factor ANOVA setting with random effects for subject and occasions (say 2 occasions) typically we estimate one variance component for each factor. To put your argument in the ANOVA setting would be to say that you can estimate a variance component for subject (between-subject), a variance component for occasion 1, and a variance component for occasion 2 and hence you are estimating 3 variance components not 2. I need to work through your 'thought experiment' but I will say this, when n is small say, 2 to 4 occasions, the SD of CLavgi will not be the BSV. So if your thought experiment does work out it will only work for large n (you have to have a large enough n to "average out" the within-subject (between-occasion) variability). Typically, when these large sample arguments are made to "average out" within-subject variability it is assumed that the within-subject variability is the same across the within-subject factor (i.e., occasions). You are not making that assumption and so I want to work through the math/stat to see what happens. Ken