Causal Analysis after Haavelmo
---- Acknowledgements -----
We thank Olav Bjerkholt for very helpful comments, participants at the Haavelmo symposium, Oslo, Norway, December, 2011, as well as Steven Durlauf, Maryclare Griffin and Cullen Roberts, three anonymous referees, participants in the seminar on Quantitative Research Methods in Education, Health and Social Sciences at the University of Chicago, March 2013, and participants at a seminar at UCL, September 4, 2013. Steve Stigler gave us helpful bibliographic references. This research was supported in part by the American Bar Foundation, a grant from the European Research Council DEVHEALTH-269874, and NICHD R37-HD065072. The views expressed in this paper are those of the authors and not necessarily those of the funders or commentators mentioned here, nor of the National Bureau of Economic Research.