Table 3.

Model comparison for the Cocaine example

	Model	Number of free parameters/rat	k	log(ML)	AICc	Δ
Phase 1	Default (unconstrained)	9	180	−10359	21097	26
	c = 0	8	160	−10440	21216	145
	Ω = 0	8	160	−10368	21071	0
	c, Ω = 0	7	140	−10445	21183	112
Phase 2	Default (Ω = 0)	8	160	−10368	21071	35
	γ = 0	7	140	−10372	21036	0
	α = 0	7	140	−10389	21070	34
	γ, α = 0	6	120	−10411	21071	36
	γ = α = β	6	120	−10418	21085	49

Note. Each model is identified by its constraints (Model column). The default model for Phase 2 is the model selected (lowest Δ) in Phase 1. The total number of observations, n, was 3521. The number of rats, N, was 20.