Figure 4.

A univariate dual change score model to examine trajectories on grade level changes for each indicator (X). The model includes an estimate for intercept (g₀), mean intercept (µ₀), and mean slope (µ₁). Notes: The α represents constant changes and defines the form of the slope factor g₁ (i.e., a=1 is linear change). The β represents the size of the proportional auto-regressive changes. A correlation between the intercept and slope (ρ₀₁) is allowed, and the error variance (ψ²) is assumed to be constant at each grade level.