Table 2.
Item response characteristics for the three measures of suicidality
| Discrimination parameter (α) | Response option thresholds | ||||||
| β1 | β2 | β3 | β4 | β5 | β6 | ||
| MADRS suicidality | 7.1 | 0.03 | 0.8 | 1.53 | 1.93 | 2.57 | 2.97 |
| HRSD-17 suicidality | 6.1 | 0.4 | 1.26 | 1.99 | 3.11 | ||
| BDI suicidality | 3.1 | 0.64 | 1.98 | 2.66 | |||
The threshold parameter β shows the standardised level of severity at which subsequent response options become more likely than the previous response option.
BDI = Beck Depression Inventory; HRSD = Hamilton Rating Scale for Depression; MADRS = Montgomery-Asberg Depression Rating Scale.