On Field Experiments

Two quick thoughts:

  1. The world is a better place because more and more policymakers realize that evidence-based policymaking beats flying blind in the dark. Now if only we invested more in passing policy design, implementation, and evaluation skills to bureaucrats….
  2. Whenever academics get involved in field experiments, we typically try to maximize the likelihood of publication (see Humphreys below). But what is good for journal reviewers may not always be useful for policymakers. This is not necessarily a bad thing. We just need to be up front about it, and have it inform our evaluation of the ethics of specific interventions.

Below are some excellent posts (both old and new) on the subject.

NYU’s Cyrus Samii:

Whether one or another intervention is likely to be more effective depends both on the relevant mechanisms driving outcomes and, crucially, whether the mechanisms can be meaningfully affected through intervention. It is in addressing the second question that experimental studies are especially useful. Various approaches, including both qualitative and quantitative, are helpful in identifying important mechanisms that drive outcomes. But experiments can provide especially direct evidence on whether we can actually do anything to affect these mechanisms — that is, experiments put “manipulability” to the test.

Columbia’s Chris Blattman:

I’m going to go even further than Cyrus. At the end of the day, the great benefit of field experiments to economics and political scientists is that it’s forced some of the best social scientists to try to get complicated things done in unfamiliar places, and deal with all the constraints, bureaucrats, logistics, and impediments to reform you can imagine.

Arguably, the tacit knowledge these academics have developed about development and reform will be more influential to their long run work and world view than the experiments themselves.

Columbia’s Macartan Humphreys on the ethics of social experimentation:

Social scientists are increasingly engaging in experimental research projects of importance for public policy in developing areas. While this research holds the possibility of producing major social benefits, it may also involve manipulating populations, often without consent, sometimes with potentially adverse effects, and often in settings with obvious power differentials between researcher and subject. Such research is currently conducted with few clear ethical guidelines. In this paper I discuss research ethics as currently understood in this field, highlighting the limitations of current approaches and the need for the construction of appropriate ethics, focusing on the problems of determining responsibility for interventions and assessing appropriate forms of consent.

…. Consider one concrete example where many of the points of tension come to a head. Say a researcher is contacted by a set of community organizations that want to figure out whether placing street lights in slums will reduce violent crime. In this research the subjects are the criminals but seeking informed consent of the criminals would likely compromise the research and it would likely not be forthcoming anyhow (violation of the respect for persons principle); the criminals will likely bear the costs of the research without benefitting (violation of the justice principle); and there will be disagreement regarding the benefits of the research—if it is effective, the criminals in particular will not value it (producing a difficulty for employing the benevolence principle). Any attempt at a justification based on benevolence gives up a pretense at neutrality since not everyone values outcomes the same way. But here the absence of neutrality does not break any implicit contract between researchers and criminals. The difficulties of this case are not just about the relations with subjects however. Here there are also risks that obtain to nonsubjects, if for example criminals retaliate against the organizations putting the lamps in place. The organization may be very aware of these risks but be willing to bear them because they erroneously put faith in the ill-founded expectations of researchers from wealthy universities who are themselves motivated in part to publish and move their careers forward.

University of Maryland’s Jessica Goldberg (Africanists, read Golberg’s work):

Researchers have neither the authority nor the right to prohibit a control group from attending extra school, and they cannot require attendance from the treatment group. Instead, researchers randomly assign some study participants to be eligible for a program, such as tutoring.  Those in the control group are not eligible for the tutoring provided by the study, but they are not prohibited from seeking out tutoring of their own.

The difference may seem subtle, but it is important.  The control group is not made worse off or denied access to services it would have been able to access absent the experiment. It might not share in all of the benefits available to the treatment group, but that disadvantage is not necessarily due to the evaluation.

Georgetown’s Martin Ravallion:

I have worried about the ethical validity of some RCTs, and I don’t think development specialists have given the ethical issues enough attention. But nor do I think the issues are straightforward. So this post is my effort to make sense of the debate.

Ethics is a poor excuse for lack of evaluative effort. For one thing, there are ethically benign evaluations. But even focusing on RCTs, I doubt if there are many “deontological purists” out there who would argue that good ends can never justify bad means and so side with Mulligan, Sachs and others in rejecting all RCTs on ethical grounds. That is surely a rather extreme position (and not one often associated with economists). It is ethically defensible to judge processes in part by their outcomes; indeed, there is a long tradition of doing so in moral philosophy, with utilitarianism as the leading example. It is not inherently “unethical” to do a pilot intervention that knowingly withholds a treatment from some people in genuine need, and gives it to some people who are not, as long as this is deemed to be justified by the expected welfare benefits from new knowledge.


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