Good article, and useful further links in comments. Thanks to all who have contributed. But do you really think this is impact ? By whose definition ? The results you include in your examples are outcomes, not impacts. Medium term and long term outcomes to be sure, but not impacts. Outcomes are behaviour changes by other people, e.g. going to school instead of not going to school. The impact is the societal level benefit of a generation of better educated children. Or the outcome (behaviour change) is an increase in consumption activity, which then leads to society level impacts of increased health, wellbeing, etc (or does not lead to positive impact if the increased consumption is all spending on alcohol, drugs, or prostitution). Impacts are very difficult to measure in less than a few years, and there is a widespread illusion that measuring outcomes can be called measuring impacts. There are lot of good reasons why this is not the case. Measuring outcomes is really important and far too rarely done, and even less commonly based on measurements and observations. Calling it what it isn't doesn't help and is a bit disappointing in an otherwise good and useful guide. Let's encourage better measurement of medium and long term outcomes.