Table 2.

Bayesian Information Criterion (BIC) for four candidate models (normal, Poisson, Negative Binomial (NB) and Zero-Inflated Poisson (ZIP) distribution) and the ZIP parameters (intensity λ, proportion of zero-inflation p) for the Domain Scores of each NPI item. A lower value of BIC indicates a better fit to the data.

	Bayesian information criteria
	Normal	Poisson	NB	ZIP
					λ	p
Nursing home cohort: 2004
Delusions	4534	5482	3843	2904	6.00	0.63
Hallucinations	4108	4145	2101	2203	4.95	0.74
Agitation	4454	5292	3137	3104	5.51	0.57
Depression	4326	4887	2975	3108	4.80	0.57
Anxiety	4406	5112	2676	2612	5.84	0.66
Euphoria	NC*	NC*	NC*	NC*	5.40	0.90
Apathy	4643	5906	3162	2999	6.62	0.60
Disinhibition	4435	5171	2729	2780	5.67	0.65
Irritability	4442	5253	3417	3403	5.23	0.49
Motor	4623	5789	2361	2069	8.09	0.75
Sleep	4171	4499	2394	2250	5.43	0.71
Appetite	4268	4528	1777	1606	7.23	0.82
Nursing home cohort: 2011
Delusions	7374	8847	4819	4956	5.71	0.61
Hallucinations	6603	6419	3100	3301	4.96	0.77
Agitation	7294	8655	5147	5165	5.43	0.56
Depression	7006	7803	5028	5330	4.46	0.52
Anxiety	7174	8254	4555	4593	5.43	0.63
Euphoria	4950	3181	1503	1485	4.13	0.90
Apathy	7425	9096	5102	4930	6.04	0.59
Disinhibition	7346	8796	5055	5102	5.59	0.58
Irritability	7288	8643	5821	5886	5.15	0.45
Motor	7507	9285	2361	2069	7.35	0.72
Sleep	6921	7611	4310	4196	5.15	0.65
Appetite	7020	7562	3043	2808	7.04	0.81

Note. Patients with dementia of all causes living in nursing homes. One cohort included in 2004 and another in 2011.

^*NC, not computable due to extreme zero-inflation.