Table 4 Differential item functioning positive and negative symptoms: reference group = USA vs. focal group = Northern European, Southern Europe and Russia & Ukraine

Item

Chi-sq

p-value

E.S. (95% C.I.)

Class

Northern Europe Mean

Chi-sq

p-value

E.S. (95% C.I.)

Class

Southern Europe Mean

Chi-sq

p-value

E.S. (95% C.I.)

Class

Russo Europe

USA Mean

P1

0.79

0.38

−0.02 (−0.21;0.17)

A

4.60 (1.06)

27.73

< 0.001

−0.56 (−0.76;-0.35)

B-

3.66 (0.75)*

6.06

0.01

−0.31 (−0.50;-0.12)

BB-

3.86 (0.84)

4.29 (1.05)

P2

4.16

0.04

0.22 (−0.04;0.48)

A

3.97 (0.99)

26.9

< 0.001

0.83 (0.56;1.10)

C+

4.05 (1.34)*

6.58

0.01

0.34 (0.12;0.55)

BB+

3.56 (0.77)

3.42 (1.34)

P3

3.93

0.05

0.12 (−0.03;0.27)

A

4.79 (0.68)

4.48

0.03

0.20 (0.03;0.38)

A

4.24 (0.82)

8.68

< 0.001

0.24 (0.09;0.38)

AA

4.40 (0.84)*

4.33 (0.96)

P4

0.84

0.36

−0.07 (−0.26;0.12)

A

3.11 (1.13)

2.55

0.11

−0.18 (−0.35;-0.01)

A

2.07 (1.25)

0.42

0.52

−0.04 (−0.21;0.12)

AA

2.40 (1.24)

2.70 (1.80)

P5

0.4

0.53

0.12 (−0.06;0.31)

A

3.98 (1.43)

40.17

< 0.001

−0.63 (−0.83;-0.42)

C-

2.10 (1.49)*

2.2

0.14

−0.04 (−0.23;0.15)

AA

2.87 (1.40)

3.34 (1.33)

P6

15.42

< 0.001

−0.33 (−0.51;-0.15)

B-

4.46 (0.88)*

12.95

< 0.001

−0.39 (−0.59;-0.20)

B-

1.09 (0.81)*

27.12

< 0.001

−0.59 (−0.80;-0.39)

BB-

3.88 (1.20)*

4.64 (1.02)

P7

0.3

0.59

−0.04 (−0.25;0.18)

A

3.39 (0.93)

56.93

< 0.001

0.72 (0.53;0.91)

C+

3.32 (1.03)*

14.33

< 0.001

0.41 (0.22;0.60)

BB+

3.21 (1.13)*

3.05 (1.26)

N1

34.81

<0.001

−0.56 (−0.76;-0.36)

BB-

3.91 (1.30)*

1.89

0.17

−0.09 (−0.24;0.05)

AA

4.46 (1.29)

0.4

0.53

−0.03 (−0.26;0.19)

AA

4.10 (1.09)

4.01 (1.67)

N2

0.6

0.44

0.07 (−0.05;0.20)

AA

3.94 (0.55)

0.46

0.5

0.03 (−0.07;0.12)

AA

4.02 (0.61)

0.48

0.49

−0.08 (−0.22;0.06)

AA

3.63 (0.76)

3.85 (0.79)

N3

1

0.32

0.10 (−0.08;0.27)

AA

3.56 (1.30)

30.61

< 0.001

0.44 (0.29;0.59)

BB+

4.04 (1.23)*

7.54

0.01

0.20 (0.05;0.34)

AA

3.24 (0.85)

3.26 (1.51)

N4

0.01

0.93

0.01 (−0.16;0.17)

AA

3.84 (0.99)

37.25

< 0.001

−0.55 (−0.70;-0.39)

BB-

3.49 (0.84)*

2.27

0.13

0.02 (−0.15;0.19)

AA

3.52 (0.87)

3.74 (1.23)

N5

0.03

0.86

−0.03 (−0.23;0.18)

AA

4.41 (1.14)

15.71

< 0.001

−0.36 (−0.55;-0.18)

BB-

4.04 (1.07)*

7.78

0.01

−0.24 (−0.44;-0.04)

AA

3.94 (0.94)

4.16 (1.32)

N6

0.93

0.33

0.06 (−0.12;0.24)

AA

3.99 (1.39)

20.58

< 0.001

0.36 (0.20;0.51)

BB+

4.39 (1.30)*

9.07

< 0.001

0.02 (−0.17;0.21)

AA

3.54 (1.08)*

3.52 (1.73)

N7

10.44

<0.001

0.35 (0.15;0.56)

BB+

3.25 (0.86)*

2.44

0.12

0.18 (−0.00;0.37)

AA

3.21 (0.99)

0.33

0.57

0.11 (−0.06;0.29)

AA

2.89 (0.77)

2.17 (1.15)