Table 5.

Internal consistency and test–retest reliability of the SCI-SC (N = 343)

	Cronbach’s alpha		McDonald’s omega		ICC (95% CI)	SEM
	Baseline	Follow-up	Baseline	Follow-up		Baseline	Follow-up
SCI	0.811 (0.781, 0.841)	0.835 (0.809, 0.862)	0.805 (0.772, 0.837)	0.832 (0.805, 0.860)	0.829 (0.792, 0.859)	2.656	2.651
SPS	0.715 (0.667, 0.763)	0.749 (0.708, 0.789)	0.749 (0.706, 0.791)	0.782 (0.745, 0.819)	0.831 (0.794, 0.861)	1.337	1.291
DIS	0.864 (0.839, 0.889)	0.887 (0.866, 0.908)	0.864 (0.839, 0.889)	0.888 (0.867, 0.908)	0.714 (0.657, 0.762)	1.178	1.218

Notes: Standard error of measurement was calculated as “SD × sqrt (1-ICC)”

Abbreviations: SCI Sleep Condition Indicator, SC simplified Chinese, ICC intraclass correlation coefficient, CI confidence interval, SEM standard error of measurement, SPS Sleep Pattern Subscale, DIS Daytime Impact Subscale, SD standard deviation