The Field Guide › Paper
A foundational text in programme evaluation methodology, addressing the problem that planned social interventions rarely produce their intended effects cleanly — and that the complexity of historical change makes attribution deeply difficult. Introduces the concept of the 'experimenting society' and argues for quasi-experimental designs as the honest alternative to either randomised trials or unevaluated implementation. Essential background for anyone making empirical claims about PS interventions: the question 'did this work?' is almost always harder to answer than it looks, and Campbell's framework explains why.