Table 1 Overview of fit statistics by country and in total

Item set

1

2

3

1

2

3

1

2

3

Items (n)

23

23

22

23

23

22

23

23

22

Persons (n)

121

126

116

115

117

111

236

243

227

Item difficulty

0.58

0.58

0.51

0.46

0.45

0.48

0.53

0.52

0.49

Cronbach’s alpha

0.78

0.76

0.72

0.70

0.73

0.75

0.77

0.77

0.74

Person separation index^a

0.72

0.69

0.62

0.57

0.64

0.66

0.70

0.71

0.64

Items with underfit (overfit)

1 (1)

3 (0)

0 (0)

3 (0)

3 (0)

7(1)

7 (3)

3 (3)

1 (1)

Overall model fit: p-values for bootstrap estimation^b

0.03*

0.13

0.43

0.08

0.65

0.53

0.03*

0.18

0.73