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 |