Table 2.

Parameter estimates for models of varying complexity.

Model						Mean estimated value
#	θ	β	α	γ	Priors	θ	β	θ−β	α	γ
1	Individual	Individual	Individual	Group	Weak	—	—	—	—	—
2	Individual	Individual	Individual	Group	Strong	0.76	−1.03	1.79	1.13	0.59
3	Individual	Individual	Group	Group	Weak	−0.14	0.11	−0.25	3.43	0.84
4	Individual	Individual	Group	Group	Strong	0.57	−1.01	1.58	1.41	0.59
5	Individual	Group	Group	Group	Weak	−0.01	−1.70	1.69	1.25	0.52
6	Individual	Group	Group	Group	Strong	0.06	−1.79	1.73	1.06	0.52

Note: “Individual” refers to the estimation of unique parameter values for each subject (θ) or each item (β, α, and γ). “Group” refers to the estimation of one value for all items. “Weak” item priors allow estimates to be based on observed data without the influence of “Strong” prior beliefs. θ, subject ability parameter; β, item difficulty parameter; α, item discrimination parameter; γ, item guessing parameter.