These days we talk a lot about how best to assess development impact through evaluative research. Sound data and methods are essential. Here there has been considerable progress over the last 20 years or so.
All that progress will come to nothing if it does not make those people actually doing development more knowledgeable about what they are doing. This depends in part on whether the research that is done is useful and well disseminated. Here there has also been progress, though more work is needed.