In "A Primer on Effectiveness and Efficacy Trials" (Clinical and Translational Gastroenterology(2014) 5), Amit G Singal MD, MS, Peter D R Higgins MD, PhD and Akbar K Waljee MD, MS, explain:
Intervention studies can be placed on a continuum, with a progression from efficacy trials to effectiveness trials. Efficacy can be defined as the performance of an intervention under ideal and controlled circumstances, whereas effectiveness refers to its performance under ‘real-world’ conditions.1 However, the distinction between the two types of trial is a continuum rather than a dichotomy, as it is likely impossible to perform a pure efficacy study or pure effectiveness study. (source, see also here)
This method appears to be on the horizon of those who influence the cultures of the education industry (here, here, here, and here).
Goldie Blumenstyk has recently reported for the Chronicle of Higher Education about the release of papers from a first of its kind symposium on efficacy research hosted by the University of Virginia: