Why control groups are ethical and necessary in the Huffington Post: “the importance of knowing whether or not new methods add to student outcomes is so great that one could argue that it is unethical not to agree to participate in experiments in which one might be assigned to the control group”
Recently both the American Economic Association and 3ie have launched Impact Evaluation Trial Registries. The basic idea in both cases is for researchers to register in advance the details of an evaluation they are planning on doing. This has a couple of main purposes:
There has been a lot of recent debate and discussion about the role of cash grants in aid, and whether aid is more effective when simply given as unrestricted cash compared to approaches such as conditional transfers which try to restrict how recipients use any money received. Traditionally this debate has centered around food aid and education funding, but more recently this discussion has also arisen with respect to funding small businesses.
A common critique of many impact evaluations, including those using both experimental and quasi-experimental methods, is that of external validity – how well do findings from one setting export to another? This is especially the case for studies done on relatively small samples, although as I have ranted before, there appears to be a double standard in this critique when compared to both other disciplines in economics and to other development literature.