Appendix A3.
Test statistics of the Differential Item Functioning analysis: Step 3
| Gamblers in the general population | Slot machine gamblers sample | |||||||||
| Criterion | Hypothesis Test | G21 | d.f. | a | b | a | b | μ | δ | |
| 1 Preoccupation | All | equal | 20.1 | 2 | 0.94 | −0.63 | 1.7 | 0.54 | 1.09 | 0.88 |
| a | equal | 2 | 1 | 1.49 | −0.5 | 1.49 | 0.49 | 1.09 | 0.93 | |
| b | equal | 18.2 | 1 | 1 | 0.03 | 1 | 0.03 | 1.02 | 0.99 | |
| 2 Tolerance | All | equal | 9.2 | 2 | 2.03 | 0.42 | 1.13 | 1.19 | 0.99 | 0.8 |
| a | equal | 2.5 | 1 | 1.31 | 0.56 | 1.31 | 1.18 | 1.01 | 0.78 | |
| b | equal | 6.7 | 1 | 1.07 | 1.08 | 1.07 | 1.08 | 0.98 | 0.8 | |
1
Values exceeding 3.84 (the α = 0.05 critical value of the χ2 distribution, when df = 1) are considered as significant difference (Thissen, 2001).