摘要 : Field experiments are popular again in policy circles. There are various types of field experiments, with complementary strengths and weaknesses for different policy questions. There is also a lot of needless hype about what field... 展开 Field experiments are popular again in policy circles. There are various types of field experiments, with complementary strengths and weaknesses for different policy questions. There is also a lot of needless hype about what field experiments can do. More balance in our use of field experiments is called for. 收起