Table 3 Results of the item-total correlation and the reliability (Cronbach's alpha) for the reduced version as well as for the initial 22-item

N° of items

22

10

6

4

Scoring distribution

Valid observations

132

133

134

134

Mean

44.9

44.6

38.8

53.4

SD

17.5

22.3

23.9

29.3

Percentile 50

43.7

40

37.5

53.1

% scoring 0

0

0

5

3 (2.2%)

% scoring 100

0

1

2

8 (5.9%)

Correlation item-global scoring

0.21–0.72

0.53–0.73

0.65–0.79

0.78–0.89

Reliability (Cronbach's alpha)

0.87

0.86

0.84

0.86

Results of Rasch analysis

Person separation

2.28

2.21

1.87

1.79

Person reliability

0.84

0.83

0.78

0.76