Acknowledgment of any conceptual or methodological constraints
Radio programming was one of the key elements of our program however, it was difficult to fully control contamination between intervention and control areas. For this, initially, the program was broadcast at a specific time (days and hours) which was known only to the families in the intervention group. In addition, we used the least listened-to radio station among 17 covering Ngororero district, based on our baseline assessment which successfully decreased contamination. 15% of participants in the control arm reported having listened to the radio and this spillover was controlled in the analysis. During the TtS phase in Ruhango, Gasabo and Kirehe the approach used was the same and a few families in a control group listened to one or two radio soap operas but not regularly enough to affect the results. The endline assessment showed that the intervention group had greater gains in parental practices and child outcomes.Monitoring data also showed that some challenges were encountered in the first few weeks of implementation in 2015 but these were quickly addressed through course correction activities. For example, a few weeks after the start of the 2015 RCT, full and light interventions had a small difference due to logistical constraints in accessing books and other inputs. The importance of good logistical planning was noted for future programming and also this limitation was noted in the 2016 RCT end-line study report (In regards to advocacy, it is always important to recognize that advocacy is done in partnership with others so although Save the Children played an influential role in shaping policy around 0–3 ECD, it was in collaboration with other partners including the members of the Rwanda Education NGOs Coordination Platform (RENCP) ECD Working group, Imbuto Foundation, and UNICEF.