Assessment of the Psychometric Properties of the Holland Sleep Disorders Questionnaire in the Iranian Population

Table 2

The ratio and index of content validity and multivariate normality index of the tool items.

No.	Items	CVR^a	CVI^b	Kurtosis^c	Skewness^d
1	During the day, I suffer from fatigue.	0.83	0.92	0.48	−0.7
2	When I lie down in bed, I experience unpleasant, itchy, or burning sensations in my legs.	0.67	0.92	1.65	1.26
3	I wake up with a dry mouth in the morning.	0.67	1	1.47	1.29
4	I wake up in the middle of the night, screaming and/or heavily perspiring and feeling anxious.	0.83	0.92	2.48	1.2
5	I do not fall asleep until the morning and have great difficulty waking up early. I sleep in on weekends.	0.83	1	1.5	1.71
6	When I experience ‘restless legs’, I can suppress these sensations by walking or stretching my legs.	0.67	0.83	1.78	1.1
7	The quality of my sleep is poor and I do not feel well rested in the morning.	0.67	0.92	0.38	1.07
8	When I am sitting still, especially in the evenings, I feel an urge to move my legs.	0.50	0.92	1.83	1.68
9	I move my arms or legs during sleep.	0.83	0.83	1.29	1.47
10	At night, I lie awake for a long time.	0.83	0.92	−0.52	0.87
11	While asleep I suffer from kicking leg movements that I just cannot suppress.	0.67	1	−0.13	0.69
12	I worry about the consequences of my poor sleep (e.g., for my health).	0.83	0.83	1.93	1.67
13	I have difficulty falling asleep at night.	0.50	0.92	0.22	0.01
14	Especially after a bad night, I suffer from one or more of the following consequences: fatigue, sleepiness, bad mood, poor concentration, memory problems, and lack of energy.	0.50	0.92	−0.21	0.4
15	Despite having plenty of opportunity to sleep in, I do not get enough sleep.	0.50	0.92	0.006	0.01
16	I regularly have vivid dreams in which I am being attacked and try to defend myself with uncontrolled movements.	0.83	0.92	1.17	0.74
17	I stop breathing during sleep.	0.83	1	−0.17	1.04
18	I snore loudly while I am asleep.	0.67	0.83	−1.07	0.68
19	At night I wake up with a start feeling like I am choking.	0.67	0.92	1.37	1.62
20	I suffer from nightmares or bad dreams.	0.83	0.83	1.67	0.62
21	Because of insufficient sleep, I do not function as well during the day.	0.50	0.92	0.77	1.34
22	I have injured myself during sleep and had no recollection of the event afterwards.	0.83	0.83	1.46	0.32
23	I fall asleep repeatedly throughout the day.	0.50	0.92	1	−1.09
24	Quite often I partially wake up and find myself thrashing my arms. I usually do not recall this later on.	0.50	0.83	2.7	0.89
25	After a daytime nap I do not feel refreshed.	0.67	0.92	2.9	1.86
26	I sleep poorly because I do not manage to fall asleep at a normal hour and wake up at a normal hour in the morning.	0.83	0.92	2.2	1.02
27	When I have to stay awake during the night, my daytime sleep is poor.	0.83	0.83	2.9	1.6
28	I usually sleep more than 10 hours a night, have difficulty waking up in the morning, and nap during the day.	0.67	1	1.3	0.9
29	During the day, I suffer from sleep attacks that are so severe that I cannot suppress them.	0.67	0.92	1.2	1.6
30	The time at which I fall asleep varies strongly from day to day.	0.50	0.92	1.4	0.4
31	I suffer from sleepwalking.	0.50	0.92	2.3	1.9
32	During the day, I fall asleep involuntarily, especially in monotonous situations (e.g., during a boring TV show).	0/83	0.92	2.7	1.9

^aContent validity ratio: the content validity ratio (Lawshe) is one of the earliest and most widely used methods for quantifying content validity. ^bContent validity index is the most widely used index in quantitative evaluation. ^cSkewness is a measure of symmetry or, more precisely, the lack of symmetry. ^dKurtosis is a measure of whether the data are heavy-tailed or light-tailed relative to a normal distribution.