On Two Approaches to Weighting in Causal Inference

^aDepartment of Statistics, Columbia University, New York, NY; ^bDepartment of Health Care Policy, Harvard Medical School, Boston, MA; and ^cDepartment of Statistics, Faculty of Arts and Sciences, Harvard University, Cambridge, MA.

Editor’s Note: Related article appears on p. 802.

The authors report no conflicts of interest.

Supported by a grant from the Alfred P. Sloan Foundation.

Supplemental digital content is available through direct URL citations in the HTML and PDF versions of this article (www.epidem.com).

Correspondence: José R. Zubizarreta, Department of Health Care Policy, Harvard Medical School, 180 Longwood Avenue, 307-D Boston, MA. E-mail: [email protected].