What is the difference between internal and external evaluation? When is an evaluation formative or summative? What about lesson learning and accountability?

Internal/External
 
Is the exercise primarily internal or external?
 
One of the major differences for any kind of assessment or evaluation is whether it is undertaken by staff and beneficiaries, or by external, independent, evaluators.
 
Broadly speaking, independent evaluators have no stake in the outcome of the evaluation exercise and have had no involvement in the project/programme activities. Thus, one function of external evaluations is to improve accountability, by providing an objective basis from which to account to the principal stakeholders. The main stakeholders include the people affected by the project including country government and civil society representatives, the funders who are often tax payers, and the organisation managing the work and their partners.

Formative/Summative

Evaluations undertaken during the project/ programme cycles are formative in the sense that they can lead to changes in the strategy and/or methodology of the project/ programme. Those undertaken when the project/ programme has finished are summative, being used for lesson learning and accountability. 

Lesson learning and accountability
 
These concepts are often linked together since they summarise the main purposes behind evaluation exercises. Evaluators are divided as to how much these two purposes can be achieved from a single study. Lesson learning is intended to help understanding of why particular aid activities have been more or less successful, in order to improve performance.
 
Accountability is mainly concerned with accounting to funders and beneficiaries for the use of the money. In either case the evaluation is intended to help to organisation learn from its experiences.

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