Item | IRT Parameters | Factor loadings | Uniqueness | Item test correlation | Item rest correlation | Average interitem covariance | Item Cronbach’s Alpha | |||
---|---|---|---|---|---|---|---|---|---|---|
α | b1 | b2 | b3 | |||||||
PHQ1: Interest | 2.00 | −0.04 | 1.94 | 2.41 | 0.722 | 0.479 | 0.719 | 0.619 | 0.177 | 0.814 |
PHQ2: Hopeless | 1.78 | 0.25 | 2.26 | 2.57 | 0.717 | 0.486 | 0.690 | 0.583 | 0.181 | 0.818 |
PHQ3: Sleep | 1.40 | 0.12 | 1.94 | 2.25 | 0.582 | 0.661 | 0.620 | 0.466 | 0.182 | 0.835 |
PHQ4: Tired | 1.83 | −0.31 | 1.93 | 2.17 | 0.701 | 0.508 | 0.720 | 0.611 | 0.174 | 0.815 |
PHQ5: Appetite | 1.29 | 0.40 | 2.25 | 2.69 | 0.564 | 0.682 | 0.629 | 0.490 | 0.183 | 0.830 |
PHQ6: Failure | 1.78 | 1.53 | N/R | 2.71 | 0.747 | 0.443 | 0.651 | 0.558 | 0.191 | 0.822 |
PHQ7: Concentrating | 1.74 | 0.56 | 2.31 | 2.51 | 0.728 | 0.469 | 0.712 | 0.610 | 0.178 | 0.815 |
PHQ8: Moving | 2.08 | 0.60 | 2.32 | 2.57 | 0.753 | 0.433 | 0.718 | 0.627 | 0.181 | 0.814 |
PHQ9: Suicidal ideation | 1.63 | 2.0 | N/R | 3.44 | 0.737 | 0.457 | 0.535 | 0.456 | 0.209 | 0.833 |
Overall PHQ-9 | 0.184 | 0.839 | ||||||||
Overall PHQ-2 | 0.606 |