An evaluation of computerized adaptive testing for general psychological distress: combining GHQ-12 and Affectometer-2 in an item bank for public mental health research

Stochl, Jan; Böhnke, Jan R.; Pickett, Kate E.; Croudace, Tim J.

doi:10.1186/s12874-016-0158-7

Table 2 IRT parameter estimates (in logistic metric) of GHQ-12 and Affectometer-2 items

From: An evaluation of computerized adaptive testing for general psychological distress: combining GHQ-12 and Affectometer-2 in an item bank for public mental health research

Item	Abbreviated item wording	Nr. of times Administered^a		α	t₁	t₂	t₃	t₄
Item	Abbreviated item wording	θ_true ~ N(0,1)	θ_true ~ U(-3,3)	α	t₁	t₂	t₃	t₄
GHQ 1	Able to concentrate	140	1105	1.75	−3.95	3.08	5.75	-
GHQ 2	Lost sleep	2295	2010	1.53	−0.32	1.99	3.63	-
GHQ 3	Play useful part	865	2627	1.27	−2.50	3.12	4.81	-
GHQ 4	Making decisions	560	2286	1.46	−3.07	3.97	6.08	-
GHQ 5	Under strain	4071	4265	1.87	−1.13	1.93	4.11	-
GHQ 6	Overcome difficulties	4618	2279	2.07	0.04	3.08	4.69	-
GHQ 7	Enjoy day-to-day activities	475	2152	1.42	−3.15	2.47	4.46	-
GHQ 8	Able to face problems	374	1947	1.59	−3.36	4.11	6.46	-
GHQ 9	Unhappy	7578	6138	2.94	0.01	3.17	5.48	-
GHQ 10	Lose confidence	4922	3077	2.31	0.39	2.93	5.07	-
GHQ 11	Worthless person	1055	2449	3.07	2.03	4.84	6.97	-
GHQ 12	Reasonably happy	1007	2757	1.39	−2.60	2.84	4.87	-
Aff 1	Life on the right track	8420	6903	2.01	−3.19	−0.01	1.58	3.80
Aff 2	Change life	3686	4405	1.58	−1.94	0.32	1.71	3.81
Aff 3	Future looks good	3168	4175	1.57	−3.35	−0.29	1.27	3.48
Aff 4	Best years are over	0	19	1.41	−0.02	1.47	2.56	3.70
Aff 5	Like yourself	1287	3031	1.08	−2.35	−0.14	1.33	3.16
Aff 6	Something wrong	3257	3066	2.15	0.74	2.49	3.86	5.77
Aff 7	Handle problems	751	2340	0.96	−1.81	0.38	1.60	3.25
Aff 8	Failure	4134	4193	3.35	1.48	4.03	5.48	8.33
Aff 9	Loved and trusted	1934	2901	1.29	−1.14	1.37	2.57	4.14
Aff 10	Left alone	0	9	1.34	0.60	2.06	3.19	4.81
Aff 11	Close to people	1893	3101	1.29	−1.25	1.47	2.58	4.70
Aff 12	Lost interest	0	8	1.82	1.40	2.79	4.41	6.52
Aff 13	Do whatever want	1016	2794	0.98	−2.65	−0.83	0.59	2.04
Aff 14	Life stuck	7780	8080	2.46	−0.80	1.69	3.12	5.01
Aff 15	Energy to spare	195	952	0.77	−3.84	−1.78	−0.16	1.61
Aff 16	Can’t be bothered	2493	3771	1.54	−1.56	1.04	2.48	4.91
Aff 17	Smiling a lot	1130	2881	1.28	−3.02	0.08	1.47	3.67
Aff 18	Nothing fun	3141	2230	1.67	−0.26	1.90	3.18	4.80
Aff 19	Thinking creatively	1299	3032	1.23	−2.88	0.04	1.60	3.81
Aff 20	Thoughts useless	6031	4153	2.06	−0.09	1.75	3.39	5.62
Aff 21	Satisfied	4655	4218	1.85	−3.98	−0.06	1.73	4.74
Aff 22	Optimistic	587	2307	0.92	−3.08	−0.34	0.93	2.91
Aff 23	Useful	954	2727	1.11	−2.58	0.41	1.86	3.87
Aff 24	Confident	1579	3226	1.61	−3.10	0.13	1.88	4.21
Aff 25	Understood	303	1370	0.83	−2.65	0.03	1.63	3.27
Aff 26	Interested in others	24	132	0.80	−1.66	0.86	1.99	3.75
Aff 27	Relaxed	4299	4703	1.66	−3.42	−0.26	1.41	3.70
Aff 28	Enthusiastic	1719	3348	1.31	−3.76	−0.44	1.24	3.73
Aff 29	Good natured	670	2379	0.97	−1.91	1.06	2.46	4.90
Aff 30	Clear headed	1568	3238	1.24	−2.08	0.70	1.98	4.04
Aff 31	Discontented	4462	3809	1.87	−0.74	1.69	3.22	5.16
Aff 32	Hopeless	2079	3000	3.02	1.63	3.67	5.55	7.84
Aff 33	Insignificant	2923	2417	2.32	0.93	3.02	4.58	6.39
Aff 34	Helpless	2409	2541	2.22	1.23	2.98	4.33	6.08
Aff 35	Lonely	0	9	1.64	0.31	2.04	2.98	4.89
Aff 36	Withdrawn	5565	5027	2.59	0.71	2.82	4.62	7.02
Aff 37	Tense	2763	3937	1.58	−1.67	0.75	2.19	4.24
Aff 38	Depressed	7865	6862	3.00	0.36	2.72	4.30	6.30
Aff 39	Impatient	40	231	0.77	−2.03	0.29	1.62	4.07
Aff 40	Confused	0	10	1.49	0.32	2.27	3.56	5.23

^aNumber of times the items was administered out of 10,000 simulated CAT administration for SEM = 0.32, MLE and UW-FI item selection algorithm

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