Table 6. Raw mediation statistics.
| Estimate (b) | s.e. | P-value | 95% CI (lower) | 95% CI (upper) | |
|---|---|---|---|---|---|
| Low v. normal birth weight | |||||
| Model without mediator | |||||
| Intercept | −1.18 | 0.01 | <0.001 | −1.20 | −1.16 |
| Low birth weight → MDD (Path c) | 0.11 | 0.03 | <0.001 | 0.05 | 0.17 |
| Model with mediator | |||||
| Intercept | −2.17 | 0.02 | <0.001 | −2.21 | −2.14 |
| Low birth weight → neuroticism (Path a) | 0.25 | 0.04 | <0.001 | 0.16 | 0.33 |
| Neuroticism → MDD (Path b) | 0.22 | 0.00 | <0.001 | 0.22 | 0.23 |
| Low birth weight → MDD (Path c’) | 0.07 | 0.03 | 0.040 | 0.00 | 0.13 |
| Indirect effect (Paths a * b) | 0.05 | 0.01 | – | 0.04 | 0.07 |
| Very low v. normal birth weight | |||||
| Model without mediator | |||||
| Intercept | −1.18 | 0.01 | <0.001 | −1.20 | −1.16 |
| Very low birth weight → MDD (path c) | 0.21 | 0.04 | <0.001 | 0.14 | 0.29 |
| Model with mediator | |||||
| Intercept | −2.18 | 0.02 | <0.001 | −2.12 | −2.14 |
| Very low birth weight → neuroticism (Path a) | 0.26 | 0.06 | <0.001 | 0.15 | 0.38 |
| Neuroticism → MDD (Path b) | 0.22 | 0.00 | <0.001 | 0.22 | 0.23 |
| Very low birth weight → MDD (Path c’) | 0.18 | 0.04 | <0.001 | 0.10 | 0.26 |
| Indirect effect (Paths a * b) | 0.06 | 0.01 | – | 0.03 | 0.09 |
Path a: association between predictor and mediator (i.e., low/very low birth weight → neuroticism).
Path b: the mediator→ outcome association (neuroticism → MDD) adjusted for the predictor (birth weight).
Path c: the ‘total effect’ of the predictor → outcome (low/very low birth weight → MDD).
Indirect effect: the product of Path a * Path b.