Fig 2. A Visual Depiction of the Mixed-Effects Location-Scale Model.

Effects on the left side are for the location model; effects on the right side are for the scale model for the residual variance. Curly brackets represent differences; square brackets represent (approximate) residual variance. Dashed lines represent participant-specific effects; solid lines represent sample average (or fixed) effects. Dots represents participant-specific observed physical activity; squares represent the average of the dots. γ₀₀ = location-model fixed intercept. β_0,i = participant-specific location-model intercept. e_0,i = participant-specific residual value. u_0,i = participant-specific location-model random intercept value (β_0,i−γ₀₀). δ₀₀ = fixed intercept of the residual variance. σ²_e,i = participant-specific residual variance. ω_0,i = participant-specific scale-model random intercept value (σ²_e,i−δ₀₀).