Table 4.

Individuals’ item fit statistics of original (K10) and final 7-item model

Items	Individuals’ items fit statistics of original K10					Individuals’ items fit statistics of final K7
	Location	SE	Residual	χ2	P values	Location	SE	Residual	χ2	P values
Feel tired (1)	–0.42	0.08	4.28	46.76	0.000
Feel nervous (2)	–0.11	0.09	–0.85	19.94	0.001	–0.20	0.15	–1.40	3.99	0.41
Feel so nervous (3)	0.13	0.09	–3.16	30.36	0.000	0.10	0.15	–2.66	11.01	0.03
Feel hopeless (4)	–0.06	0.08	–0.62	13.66	0.008	0.03	0.15	0.62	3.35	0.50
Feel restless or fidgety (5)	–0.22	0.09	0.46	16.88	0.002	–0.28	0.16	–0.81	3.98	0.41
Feel so restless (6)	0.08	0.09	–3.11	30.53	0.000	0.09	0.15	–2.78	8.04	0.09
Feel depressed (7)	0.26	0.09	3.87	70.15	0.000
Everything was an effort (8)	–0.15	0.08	–0.33	7.21	0.125	–0.09	0.15	–0.86	7.03	0.13
Feel so sad (9)	0.16	0.09	–0.48	9.11	0.058	0.34	0.16	–0.56	2.42	0.65
Feel worthless (10)	0.34	0.09	1.33	17.69	0.001

	Initial solution of K10	Final solution of K7
Overall model fit	262.27	39.82
df	40	28
P values	0.000	0.068
Item fit residuals (mean (SD))	0.13 (2.49)	–0.20 (1.20)
Person fit residuals (mean (SD))	–0.18 (1.24)	–0.63 (1.40)
Person Separation Index	0.84	0.84
Coefficient alpha	0.87	0.88
Unidimensionality test (% that goes beyond 95% CI)	9.33 (6.9 to 11.8)	3.34 (0.9 to 5.8)

K7, Kessler 7-item questionnaire; K10, Kessler 10-item questionnaire.