Skip to main content

Table 1 Descriptive statistics of the total sample, test of gender differences, bivariate correlations between individual ISI items, and item-total correlations among male and female adolescents

From: Validation of the German version of the insomnia severity index in adolescents, young adults and adult workers: results from three cross-sectional studies

  M SD Range Skew Kurt Gender differences
ANOVA Chi2-test
Descriptive statistics       F η2 Chi2 ϕ
Item 1 1.07 1.02 0-4 0.77 0.05 20.46*** .014 --- ---
Item 2 0.65 0.97 0-4 1.51 1.60 7.40** .005 --- ---
Item 3 0.92 1.16 0-4 1.12 0.27 6.74* .005 --- ---
Item 4 1.03 0.96 0-4 0.94 0.50 25.80*** .017 --- ---
Item 5 1.25 0.88 0-4 0.56 0.19 6.96** .005 --- ---
Item 6 1.14 0.97 0-4 0.84 0.46 3.44 .002 --- ---
Item 7 0.61 0.89 0-4 1.61 2.43 11.40** .008 --- ---
ISI total score 6.67 4.39 0-27 1.00 1.13 25.91*** .017 21.02*** .12
Bivariate correlations Item 1 Item 2 Item 3 Item 4 Item 5 Item 6 Item 7 rit
Item 1 --- .43*** .27*** .58*** .25*** .17*** .39*** .55***
Item 2 .39** --- .47*** .53*** .17*** .11** .34*** .55***
Item 3 .25*** .43*** --- .36*** .13*** .12** .28*** .42***
Item 4 .53*** .51*** .36*** --- .25*** .14*** .50*** .63***
Item 5 .23*** .24*** .16*** .34*** --- .47*** .30*** .39***
Item 6 .15*** .14*** .11** .20*** .46*** --- .17*** .28***
Item 7 .42*** .34*** .25*** .48*** .33*** .27*** --- .52***
rit .50*** .54*** .39*** .64*** .44*** .32*** .54*** ---
  1. Correlations for male participants are listed below the diagonal, correlations for girls above the diagonal. Item 1 = Difficulty falling asleep; Item 2 = Difficulty staying asleep; Item 3 = Waking up too early; Item 4 = How satisfied are you with your current sleep pattern?; Item 5 = To what extent do you consider your sleep problem to interfere with your daily functioning (e.g., daytime fatigue, ability to function at work/daily chores, concentration, memory, mood, etc.)?; Item 6 = How noticeable to others do you think your sleeping problem is in terms of impairing the quality of your life?; Item 7 = How worried/distressed are you about your current sleep problem?
  2. *p < .05, **p < .01, ***p < .001