Ex post evaluation recapitulates and judges the entire programme, particularly its impacts. Its aim is to account for the use of resources and to report on the effectiveness and efficiency of interventions and the extent to which expected effects were achieved. It focuses on factors of success or failure, and on the sustainability of results and impacts. It tries to draw conclusions that can be generalised and applied to other programmes or regions.
Ideally, the results of this evaluation should be available when the next programme is planned, that is, at least a year before the end of the programme. However, for the impacts to have been produced, ex post evaluation would have to be performed two to three years after the end of the programming period. While waiting for this period to pass, a provisional review is often requested shortly before the end of the programming cycle, in liaison with the ex ante evaluation of the following cycle.
Impact analysis is always a large-scale exercise if performed systematically. Ex post evaluations therefore tend to involve surveys in the field and to take place over long periods lasting from twelve to eighteen months.