Policy Evaluation, Randomized Controlled Trials, and External Validity - A Systematic Review
This paper reviews all Randomized Controlled Trials (RCTs) published in leading economic journals between 2009 and 2014 with respect to how they deal with potential hazards to external validity: Hawthorne and John-Henry effects, general equilibrium effects, specific sample problems, and special care in treatment provision. We find that the majority of published RCTs does not discuss these hazards and many do not provide the necessary information to assess potential problems.
Peters, J., J. Langbein und G. Roberts (2016), Policy Evaluation, Randomized Controlled Trials, and External Validity - A Systematic Review. Economics Letters, 147, 51-54