Parameter | Assumed level | Comment |
---|---|---|
Proportion of girls who sit for the grade 9 exam in control arm | 0.70 | |
Effectiveness of combined intervention vs control | +26.5% | i.e. proportion completing in combined intervention arm assumed to be 0.886 |
Effectiveness (i.e. (1-RR) × 100 of economic intervention vs control | +15% | i.e. proportion completing in economic intervention arm assumed to be 0.805 |
Effectiveness of combined intervention vs economic intervention | +10% | The combined intervention will offer a [1 + (0.886/0.805)], i.e. 10% relative increase compared to the economic intervention alone. |
Cluster size | 28 | See assumptions for the outcome “incidence of births before girls’ 18th birthday” |
ICC | 0.02 | We have no information on the ICC for this outcome but have assumed it to be higher than for pregnancy |
Z1 | 1.96 | |
Power for comparison of economic intervention vs combined intervention | 95% | We need 29 clusters in each of the intervention arms to have 95% power to detect the assumed difference |
Power for comparison of economic intervention vs control | 95% | We need 24 clusters in each of the arms to have 95% power to detect the assumed difference |
Power for comparison of combined intervention vs control | >95% | We need 7 clusters in each arm to have 95% power to detect the assumed difference |