The purpose of NONIE is to promote more and better impact evaluations among its members. Issues relating to evaluations in general are more effectively dealt with in the parent networks, and are thus not the primary focus of NONIE. NONIE will focus on sharing of methods and learning-by-doing to promote the practice of IE (impact evaluation). The current Guidance document was developed for supporting those purposes.

The Guidance is structured around nine key issues in impact evaluation:

1. Identify the (type and scope of the) intervention
2. Agree on what is valued
3. Carefully articulate the theories linking interventions to outcomes
4. Address the attribution problem
5. Use a mixed methods approach: The logic of the comparative advantages of methods
6. Build on existing knowledge relevant to the impact of interventions
7. Determine if an impact evaluation is feasible and worth the cost
8. Start collecting data early
9. Front-end planning is important

The discussion of these nine issues constitutes the structure of this Guidance document. The first part, comprising the first six issues deals with methodological and conceptual issues in IE and constitutes the core of the Guidance document. In addition, a shorter second part focuses on managing IE and addresses aspects of evaluability, benefits and costs of IE and planning. There is no universally accepted definition of rigorous impact evaluation. There are some who equate rigorous IE with particular methods and designs. In our view rigorous impact evaluation is more than a methodological design. Rigorous impact evaluation requires addressing the issues described above in an appropriate manner, especially the core methodological and conceptual issues described in part I.

* The Guidance document represents the views of the authors, who were commissioned by NONIE. Given the fact that perspectives on the definition, scope, and appropriate methods of impact evaluation differ widely among practitioners and other stakeholders, the document should not be taken to represent the agreed positions of all the individual NONIE members. The network membership and the authors recognize that there is scope to develop the arguments further in several key areas.