Table 6 Differential item functioning positive and negative symptoms: reference group = USA vs. focal group = Northern Europe, Southern Europe, Russia & Ukraine, India, Eastern Asia

Item

Chi-sq

p-value

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

Class

Chi-sq

p-value

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

Class

Chi-sq

p-value

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

Class

Chi-sq

p-value

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

Class

Chi-sq

p-value

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

Class

G1

17.54*

<0.001

0.73 (0.40;1.06)

CC+

1.74

0.19

0.19 (−0.09;0.48)

AA

12.94*

< 0.001

0.46 (0.23;0.69)

BB+

1.07

0.3

0.15 (−0.09;0.39)

AA

12.67*

<0.001

0.50 (0.24;0.76)

BB+

G2

21.95*

<0.001

−0.55 (−0.79;-0.30)

BB-

57.91*

<0.001

−0.77 (−0.98;-0.56)

CC-

12.2*

< 0.001

−0.35 (−0.55;-0.16)

BB-

36.56*

<0.001

−0.66 (−0.88;-0.45)

CC-

15.96*

<0.001

−0.47 (−0.69;-0.24)

BB-

G3

3.85*

<0.001

0.38 (0.04;0.72)

BB+

19.01*

<0.001

−0.62 (−0.91;-0.34)

CC-

8.58*

< 0.001

−0.39 (−0.64;-0.14)

BB-

13.56*

<0.001

−0.49 (−0.75;-0.24)

BB-

0.65

0.42

−0.08 (−0.33;0.17)

AA

G4

0.13

0.72

0.08 (−0.15;0.31)

AA

4.52

0.03

−0.21 (−0.38;-0.03)

AA

3.84

0.05

−0.15 (−0.34;0.03)

AA

5.85

0.02

−0.26 (−0.42;-0.10)

AA

0.96

0.33

−0.08 (−0.25;0.09)

AA

G5

0.29

0.59

−0.10 (−0.37;0.17)

AA

7.32

0.01

−0.35 (−0.57;-0.14)

BB-

4.11

0.04

0.07 (−0.13;0.27)

AA

2.01

0.16

−0.15 (−0.36;0.06)

AA

21.1*

<0.001

−0.43 (−0.63;-0.23)

BB-

G6

6.72

0.01

−0.42 (−0.71;-0.14)

BB-

96.09*

<0.001

−1.56 (−1.88;-1.24)

CC-

12.62*

< 0.001

−0.44 (−0.68;-0.20)

BB-

43.1*

< 0.001

−0.96 (−1.24;-0.67)

CC-

101.6*

<0.001

−1.42 (−1.70;-1.13)

CC-

G7

7.99*

<0.001

−0.35 (−0.56;-0.14)

BB-

14.83*

<0.001

0.33 (0.14;0.52)

BB+

0.05

0.82

−0.08 (−0.30;0.14)

AA

9.06*

< 0.001

0.28 (0.10;0.46)

AA

4.75

0.03

0.21 (0.01;0.40)

AA

G8

0.38

0.54

−0.06 (−0.27;0.14)

AA

0.24

0.63

0.01 (−0.19;0.20)

AA

19.24*

< 0.001

−0.40 (−0.61;-0.19)

BB-

1.22

0.27

0.15 (−0.03;0.33)

AA

1.95

0.16

−0.12 (−0.30;0.06)

AA

G9

12.25*

<0.001

0.47 (0.19;0.74)

BB+

0.45

0.5

−0.09 (−0.29;0.11)

AA

4.92

0.03

−0.30 (−0.49;-0.10)

AA

0.42

0.52

−0.07 (−0.29;0.15)

AA

24.13*

<0.001

0.55 (0.33;0.76)

BB+

G10

12.43*

<0.001

0.62 (0.32;0.93)

CC+

51.21*

<0.001

0.81 (0.59;1.03)

CC+

24.08*

< 0.001

0.54 (0.35;0.72)

BB+

35.63*

< 0.001

0.63 (0.42;0.84)

CC+

21.37*

<0.001

0.47 (0.25;0.69)

BB+

G11

0.03

0.86

0.00 (−0.20;0.20)

AA

38.47*

<0.001

0.64 (0.43;0.86)

CC+

0.37

0.54

−0.02 (−0.19;0.15)

AA

1.68

0.19

0.13 (−0.05;0.31)

AA

12.14*

<0.001

0.30 (0.12;0.48)

BB+

G12

3.91

0.05

0.24 (0.01;0.48)

AA

16.84*

<0.001

0.44 (0.21;0.66)

BB+

8.07*

< 0.001

0.28 (0.08;0.49)

AA

44.49*

< 0.001

0.76 (0.54;0.98)

CC+

17.92*

<0.001

0.40 (0.19;0.62)

BB+

G13

0.03

0.86

−0.12 (−0.32;0.08)

AA

46.14*

<0.001

0.61 (0.43;0.79)

CC+

19.82*

< 0.001

0.32 (0.14;0.50)

BB+

4.2

0.04

0.16 (−0.02;0.35)

AA

16.89*

<0.001

0.34 (0.16;0.52)

BB+

G14

1.73

0.19

−0.22 (−0.49;0.05)

AA

27.31*

<0.001

0.60 (0.39;0.81)

CC+

20.86*

< 0.001

0.48 (0.29;0.67)

BB+

8.34*

< 0.001

0.31 (0.10;0.53)

BB+

20.34*

<0.001

0.40 (0.21;0.58)

BB+

G15

6.35

0.01

−0.29 (−0.54;-0.04)

AA

8.39*

<0.001

0.27 (0.08;0.46)

AA

2.91

0.09

0.19 (0.01;0.37)

AA

8.29*

< 0.001

0.28 (0.08;0.48)

AA

0.04

0.84

−0.01 (−0.18;0.17)

AA

G16

7.97*

<0.001

−0.40 (−0.69;-0.11)

BB-

9.45*

<0.001

−0.31 (−0.51;-0.10)

BB-

8.93*

< 0.001

−0.21 (−0.39;-0.03)

AA

6.01

0.01

−0.27 (−0.50;-0.04)

AA

31.17*

<0.001

−0.56 (−0.77;-0.35)

BB-