How to measure the impact of capacity development intervention at the level of the beneficiaries?

An advisor has been struggling with impact measurement of capacity development intervention, in particular on the quality of service delivery of his partners. What is the impact of capacity development of an organization on its beneficiairies? How to measure this? And how to do this systematically? Furthermore, it would be nice if this method for measurement does not result in a document alone, but in an increased learning capacity of partner organizations, beneficiaries and donors alike. Smaller organizations may do good work with beneficiaries, bu

Measuring the output of capacity development interventions is easy: number of trainings, number of workshops etc. but measuring outcome is more difficult because it is about measuring behavioural change. It is not only about qualitative data, but about qualitative data.

It might be an idea to learn from other sectors how they measure impact, in order to find innovative ways forward. For instance the Dutch 'rekenkamer' the Governmental Accountant Control Institution has worked with the African Accountant Control Institutions and have developed a methodology.

Within the communities of practice theory, there is a suggestion to measure intangible outcomes by collecting 'systematic anecdotal evidence'. What can we learn from these fields of measurement?