Retrospective impact evaluation using administrative data: Lessons from a study on the effect of capitation policy withdrawal on maternal health service provision in Ghana

This case study is guided by our earlier research on the effect of the capitation policy withdrawal on maternal health service provision in Ashanti, Ghana, which was a time-series analysis. Healthcare provider payment methods affect the provision of care in general and maternal care in particular. In 2017, Ghana suspended its capitation policy in the Ashanti Region after piloting it for 5 years. Without evidence of the effect of the policy on health service provision, capitation was suspended, and Ghana missed out on learning any lessons for the future. Given that the policy was suspended and the need to learn meaningful policy lessons and bridge the gap in the literature was missed, only a retrospective evaluation using administrative data was possible. This case study walks students through the process of planning a retrospective evaluation. Critical considerations at the planning, data-acquisition, and management stages are explained. We describe the data used for our retrospective impact evaluation, the challenges that arose, and how we addressed those challenges. We also demonstrate how the retrospective design informed the analytical approach—the interrupted time-series analysis (ITSA). We explain single versus multiple ITSA and show why single ITSA was appropriate for our case study.