Using Selection on Observed Variables to Assess Bias from Unobservables when Evaluating Swan-Ganz Catheterization
提出一种利用可观测变量选择来评估不可观测因素偏误的方法，并以Swan-Ganz导管插入术为例，帮助研究者判断该手术效果评估中的偏误大小。
Using Selection on Observed Variables to Assess Bias from Unobservables When Evaluating Swan-Ganz Catheterization by Joseph G. Altonji, Todd E. Elder and Christopher R. Taber. Published in volume 98, issue 2, pages 345-50 of American Economic Review, May 2008