再Randomised control trial 2/2, December 14th 2013 P68 (無作為抽出調査)
In other areas, RCTS have revealed as much about what is not known as what is known. Microfinance, for example, does not turn the poor into entrepreneurs, as was hoped, but does make them better off：many use the tiny loans to buy television sets. It is not clear why. Poor people also buy too little preventive health care for themselves, even though the benefits are huge. RCTS show that if you charge a pittance for simple products such as bednets treated to combat malaria or water purification tablets, people do not buy them；the products have to be free. The common conclusion from such trials is that the poor's own decisions matter much more than was once thought. Even the poorest of the poor have tiny amounts of discretionary cash and their decisions about what to spend it on (bednets, for example) make a huge difference to development. This view of the poor is at odds with the one espoused by ゛Big Push゛economists, such as Jeffrey Sachs of Columbia University, who argue that people are stuck in poverty, can do little for themselves and that development should therefore consist of providing the poor with benefits - like irrigation, roads and hospitals - that spring the poverty trap. But it is also odds with critics of Big Push thinking. J-PAL's trials show not only that the poor's decision are important but that they are sometimes bad (for example, their underinvestment in health). Critics of the Big Push, such as William Easterly of New York University, say the best way to help the poor is to stand back and s top messing up their lives. In contrast, J-PAL's trials imply that there is a role for outsiders to improve the decision-making of the poor by, say, improving information or incentives. Over the past ten years, randomised trials have changed hugely. They began as ways to provide hard evidence about what was actually happening. Now they have become techniques for testing ideas that cannot be investigated in any other way. (Are teachers or trained volunteers better at providing simple remedial lessons? Do a trial.) Over the next ten years they will change again. They are likely to get more ambitious still, use ゛big data゛, engage even more with governments and probably measure things that cannot now be tested (RCTR are already measuring cortisol levels as a way of judging how policies affect people's happiness). Who knows, their proponents might even find a way to apply them to the sweeping assertions of macroeconomists.
