Figure 2.

Autoregressive and simplex model examples for the mediator process.

M₀: mediator at baseline; M₁₂: mediator at 12 weeks; M₂₄: mediator at 24 weeks; M₅₂: mediator at 52 weeks; FM₀: latent true mediator score at baseline; FM₁₂: latent true mediator score at 12 weeks; FM₂₄: latent true mediator score at 24 weeks; FM₅₂: latent true mediator score at 52 weeks. ɛ₁₂, ɛ₂₄ and ɛ₅₂ are the mediator error variances at 12, 24 and 52 weeks. One method for obtaining identification of the model in (b) is shown in the figure: all the factor loadings = 1 and var(ɛ) are set equal.