Table 2:

Definitions of all mathematic terms used in the mixed-effects model equation (Equation 4)

i	Volume index i = 1, 2, ′, 775
j	Subject identification index j = 1, 2, ′, 198
yi	logit(HPF) or log(AI) for volume i as the response variable
IDi	Subject index of volume i where IDi ∈ (1, 2, ′, 198)
Agei	Age of subject IDi minus 76.34, the average age of all 198 subjects
ICVi	Estimated total intracranial volume of subject IDi minus 1461.5, the average ICV of all 198 subjects
DXi	Diagnostic group of subject IDi, a factor with 3 levels {CN, MCI, AD}
Sexi	Sex of subject IDi, a factor with 2 levels {Male, Female}
I{statement}	Indicator function that takes on values of 1 or 0 depending on whether the statement is true or false
β0 ′ β7	Model fixed-effects parameters to be estimated and tested against null hypotheses of type Σakβk = 0
bj	Model random effects assumed to be independent and identically distributed Gaussian with mean 0 and variance σb2
ei	Random residuals assumed to be independent and identically distributed Gaussian with mean 0 and variance σe2