Table 3.

Item median, mean and frequencies and IRT item characteristics of the NPASS item bank (N = 881).

Item	Median	Mean	Scale value					Item fit statistics		Discrimination parameters	Difficulty parameters
			1	2	3	4	5*	S-X²	p S-X²	α	β1	β2	β3
1	3	3..1	3%	10%	61%	25%	1%	18.75	0.28	2.66	−2.30	−1.35	0.79
2	3	2.8	2%	13%	84%	-	1%	13.98	0.17	2.43	−2.54	−1.28	NA
3	3	2.8	8%	17%	31%	15%	28%	16.23	0.70	2.43	−1.55	−0.53	0.95
4	3	2.8	6%	21%	38%	14%	20%	27.54	0.04	3.52	−1.67	−0.53	0.94
5	3	2.5	14%	31%	31%	14%	10%	16.70	0.67	2.58	−1.29	−0.05	1.12
6	3	2.5	10%	25%	28%	10%	27%	17.12	0.45	2.70	−1.43	−0.17	1.20
7	3	2.7	5%	16%	35%	7%	36%	18.61	0.35	2.93	−1.82	−0.66	1.19
8	3	2.9	6%	20%	53%	18%	3%	20.32	0.32	2.60	−1.87	−0.76	1.03
9	3	2.6	4%	10%	12%	5%	68%	19.44	0.37	2.83	−1.36	−0.20	1.06
10	3	2.6	5%	36%	51%	9%		26.80	0.03	1.99	−2.30	−0.32	1.81
11	2	2.3	17%	35%	45%	2%		27.03	0.41	1.53	−1.45	0.07	3.01
12	1	1.6	61%	20%	17%	3%		19.81	0.34	2.10	0.35	1.08	2.49
13	1	1.6	61%	23%	14%	2%		37.44	0.01	1.89	0.35	1.28	2.77

*'did not have to'.