As a PhD student in the late 90s, randomized field trials were not yet common place in empirical development economics. Certain quasi-experimental methods such as regression discontinuity were also fairly exotic. It was the era of the “natural experiment”, when fellow PhD students scoured county newspapers at the university library for research leads. These students were looking for news of policy changes that might plausibly introduce some exogenous variation in the local market environment.
Jed Friedman's blog
My last post discussed an example of a system intervention (improvements to the pharmaceutical supply chain) and the not uncommon inferential challenge of low power from relatively few units of observation.
A quick look at the burgeoning literature on policy evaluations will reveal a preponderance of evaluations of demand side schemes such as conditional cash transfers. There is an obvious reason for this beyond the promise that such interventions hold: the technology of treatment allows for large sample randomized evaluations, either at the household or community/village level. As long as financing is sufficient to sample an adequate number of study units, study power will not be a concern.