Table 3 Number (proportion) of items showing more than a 50% reduction in NCDIF Index for each category of DIF (i.e., large, moderate, small), averaged across booklets, empirical TIMSS analyses

2019

 G4P

0.3 (0.03)

1.0 (0.12)

2.5 (0.19)

0.5 (0.06)

0.9 (0.11)

3.0 (0.22)

0.1 (0.02)

0.5 (0.06)

0.9 (0.07)

0.1 (0.01)

1 (0.12)

2.6 (0.21)

 G4E

0.3 (0.04)

1.6 (0.16)

2.2 (0.12)

0 (0.00)

1.2 (0.12)

3.8 (0.21)

0.2 (0.04)

0.6 (0.06)

1.6 (0.13)

0.4 (0.04)

0.9 (0.08)

1.8 (0.12)

 G8P

2.8 (0.17)

2.4 (0.27)

1.5 (0.14)

2.6 (0.15)

2.2 (0.24)

1.8 (0.17)

1.2 (0.06)

1.4 (0.13)

1.5 (0.13)

0.6 (0.03)

0.8 (0.12)

2.1 (0.23)

 G8E

2.0 (0.17)

2.5 (0.28)

3.7 (0.14)

1.2 (0.10)

1.9 (0.20)

4.1 (0.16)

0.4 (0.02)

0.9 (0.12)

2.9 (0.12)

0.4 (0.02)

0.9 (0.10)

4.4 (0.20)

2011

 G4

1.6 (0.18)

2.1 (0.32)

2.3 (0.22)

2.4 (0.28)

1.2 (0.19)

3.1 (0.28)

2.4 (0.13)

0.7 (0.15)

0.9 (0.18)

2.7 (0.14)

1.2 (0.31)

0.9 (0.16)

 G8

3.1 (0.21)

2.6 (0.33)

1.9 (0.21)

3.7 (0.25)

1.4 (0.18)

1.5 (0.17)

3.9 (0.20)

1.4 (0.20)

1.1 (0.16)

2.4 (0.12)

1.9 (0.23)

1.6 (0.22)