Comparison of factor structures of the Pittsburgh sleep quality index between mid- and late pregnancy among Korean women: a cross-sectional study

Table 5 Cronbach’s alpha of mid-and late pregnancy groups (n = 281)

	Total	Mid-pregnancy	Late pregnancy
Component	Corrected item-total correlation^a	Cronbach’s alpha if item is deleted^b	Cronbach’s alpha if item is deleted^b
Subjective sleep quality	.663^**	0.477	0.561
Sleep latency	.702^**	0.472	0.568
Sleep duration	.662^**	0.477	0.580
Sleep efficiency	.642^**	0.501	0.577
Sleep disturbance	.519^**	0.569	0.597
Daytime dysfunction	.365^**	0.600	0.717
Global score^c		0.565	0.649

^aThe correlations between each component and the global PSQI score
^bThe PSQI’s Cronbach’s alpha reliability coefficient for internal consistency if the specific item is removed from the scale
^cOverall Cronbach’s alpha (the overall reliability of the PSQI)
^**p < .01

ISSN: 1471-2393