The Chinese version of the Perceived Stress Questionnaire: development and validation amongst medical students and workers

Table 2 Rasch Analysis among Different Items for the C-PSQ

	DIF	Discrimination	Dimensionality	Unexplained variance in 1st contrast	Total raw unexplained variance (%)	PSI	PR
PSQ-30	2, 7, 10, 22, 26, 27	11	1, 7, 10, 13, 17, 21, 25, 29	3.2109	57.5	3.45	0.92
PSQ-17	15, 24, 28	NR	Not	1.8736	50.9	2.85	0.89
PSQ-14	16	NR	Not	1.7727	50.9	2.52	0.86
PSQ-13	NR	NR	Not	1.7043	50.3	2.42	0.85
Cut-off	< 0.5	> 0.4	Based on 1st contrast	< 2 or < 3	> 50	> 2.0	> 0.8

Abbreviation: DIF differential item functioning, PSI person separation index, PR person reliability, NR not required
If item dropped (in bold) in DIF, Discrimination, Dimensionality;
PSQ-30 retained all 30 items;
PSQ-17 removed item 1, 2, 7, 10, 11, 13, 17, 21, 22, 25, 26, 27, 29;
PSQ-14 removed item 1, 2, 7, 10, 11, 13, 15, 17, 21, 22, 24, 25, 26, 27, 28, 29;
PSQ-13 removed item 1, 2, 7, 10, 11, 13, 15, 16, 17, 21, 22, 24, 25, 26, 27, 28, 29

ISSN: 1477-7525