除了正式的标准实验,这里还有一些变体,包括自然实验和准自然实验<ref>J. DiNardo, 2008. "natural experiments and quasi-natural experiments," ''The New Palgrave Dictionary of Economics'', 2nd Edition. [http://www.dictionaryofeconomics.com/article?id=pde2008_N000142&edition=current&q Abstract.]</ref>。 | 除了正式的标准实验,这里还有一些变体,包括自然实验和准自然实验<ref>J. DiNardo, 2008. "natural experiments and quasi-natural experiments," ''The New Palgrave Dictionary of Economics'', 2nd Edition. [http://www.dictionaryofeconomics.com/article?id=pde2008_N000142&edition=current&q Abstract.]</ref>。 |