Table 6.
Cannabis-psychosis causal hypothesis and cannabis-psychosis self-medication hypothesis: within-person fixed-effect model compared with random-effects model in a combined sample of NEMESIS-2 study and EDSP study
| Predicted outcome | Model | Adjustmentb | OR | 95% LL | 95% UL | P | Observationsc | Individualsc | Hausman chi2 | Hausman P |
|---|---|---|---|---|---|---|---|---|---|---|
| Incidenta PE at t predicted by preceding cannabis use at t-1 | FE | Not adjusted | 9.16 | 3.23 | 25.97 | 0.000 | 827 | 375 | 1.01 | .32 |
| RE | 5.58 | 3.79 | 8.23 | 0.000 | 15 169 | 6240 | ||||
| FE | Adjusted | 7.03 | 2.39 | 20.69 | 0.000 | 827 | 375 | 84.18 | .000 | |
| RE | 2.29 | 1.60 | 3.28 | 0.000 | 15 169 | 6240 | ||||
| Incidenta cannabis use at t predicted by preceding PE at t-1 | FE | Not adjusted | 0.59 | 0.37 | 0.93 | 0.022 | 557 | 225 | 115.37 | .000 |
| RE | 4.27 | 3.23 | 5.64 | 0.000 | 15 671 | 6241 | ||||
| FE | Adjusted | 0.59 | 0.21 | 1.71 | 0.33 | 557 | 225 | 95.23 | .000 | |
| RE | 1.48 | 1.13 | 1.93 | 0.004 | 15 671 | 6241 |
PE, psychotic experiences; FE, fixed-effects model; RE, random-effects model; 95% LL, 95% CI lower bound; 95% UL, 95% CI upper bound; Hausman, Hausman test comparing FE with RE model.
aExcluding individuals with psychotic experiences, respectively, cannabis use at preceding interview wave.
bAdjusted for age, life events, other drugs use, and any DSM diagnosis.
cObservations are clustered within individuals, given repeated measurements over time.