However, when misinterpreted as evidence of a causal relationship between a development intervention of a programme and poverty reduction, conclusions drawn from studies solely using monitoring data can lead to ineffective or even harmful policies – and in most cases to a waste of public resources.

When are impact evaluations useful – and when not?

Impact evaluations are a tool for policy-makers and development practitioners to improve development outcomes based on evidence. The findings of impact evaluations can help organisations to decide whether to scale up projects with proven positive impacts or discontinue interventions lacking in effectiveness. Impact evaluations can also identify the specific point – of the theory of change – at which policies don’t work as planned. For instance, the Agricultural Technology Adoption Initiative (ATAI, 2016) shows that index-based weather insurance is very effective when taken up, but that at market premiums take-up is very low (6-18 per cent) – it is at the point of take-up, not after, that rainfall-index insurance programmes seem to run aground.