Table 1.

Results of parameter estimation for models of varying complexity.

Model						Results
#	θ	β	α	γ	Priors	Converged	PSD θ	PSD β	PSD α	PSD γ	DIC
1	Individual	Individual	Individual	Group	Weak	No	—	—	—	—	—
2	Individual	Individual	Individual	Group	Strong	Yes	0.19	0.71	0.53	0.01	8397.82
3	Individual	Individual	Group	Group	Weak	Yes	0.23	1.60	0.38	0.01	8482.44
4	Individual	Individual	Group	Group	Strong	Yes	0.19	0.69	0.23	0.01	8483.80
5	Individual	Group	Group	Group	Weak	Yes	0.31	0.66	0.33	0.22	8729.56
6	Individual	Group	Group	Group	Strong	Yes	0.31	0.28	0.19	0.05	8730.00

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; PSD, posterior standard deviation; DIC, deviance information criterion.