DIF on age, gender, educational attainment and socioeconomic conditions on K7 scale
| Items | DIF on age | DIF on gender | ||||||
| MS | F | df | P value | MS | F | df | P value | |
| Feel nervous | 1.81 | 2.25 | 1 | 0.135 | 1.26 | 1.55 | 1 | 0.215 |
| Feel so nervous | 1.18 | 1.46 | 1 | 0.228 | 0.14 | 0.17 | 1 | 0.682 |
| Feel hopeless | 0.85 | 0.87 | 1 | 0.351 | 3.45 | 3.61 | 1 | 0.059 |
| Feel restless or fidgety | 0.81 | 0.80 | 1 | 0.373 | 0.93 | 0.92 | 1 | 0.339 |
| Feel so restless | 2.20 | 2.79 | 1 | 0.096 | 0.16 | 0.20 | 1 | 0.655 |
| Everything was an effort | 0.25 | 0.34 | 1 | 0.560 | 0.64 | 0.88 | 1 | 0.351 |
| Feel so sad | 0.77 | 0.79 | 1 | 0.374 | 0.06 | 0.06 | 1 | 0.800 |
| Items | DIF on educational attainment | DIF on socioeconomic conditions | ||||||
| MS | F | df | P value | MS | F | df | P value | |
| Feel nervous | 0.44 | 0.55 | 1 | 0.458 | 0.00 | 0.01 | 1 | 0.939 |
| Feel so nervous | 0.19 | 0.22 | 1 | 0.637 | 0.34 | 0.41 | 1 | 0.521 |
| Feel hopeless | 0.02 | 0.02 | 1 | 0.897 | 0.84 | 0.88 | 1 | 0.351 |
| Feel restless or fidgety | 0.29 | 0.28 | 1 | 0.597 | 2.18 | 2.15 | 1 | 0.144 |
| Feel so restless | 0.02 | 0.02 | 1 | 0.883 | 0.27 | 0.34 | 1 | 0.559 |
| Everything was an effort | 1.83 | 2.48 | 1 | 0.117 | 0.48 | 0.65 | 1 | 0.421 |
| Feel so sad | 0.01 | 0.01 | 1 | 0.917 | 0.00 | 0.00 | 1 | 0.955 |
DIF, differential item functioning; MS, mean square.