Treatment Effect Bounds: An Application to Swan-Ganz Catheterization

50 Pages Posted: 25 May 2005 Last revised: 22 Jun 2009

See all articles by Jay Bhattacharya

Jay Bhattacharya

Stanford University - Center for Primary Care and Outcomes Research; National Bureau of Economic Research (NBER)

Azeem Shaikh

Stanford University - Department of Economics

Edward Vytlacil

Yale University - Department of Economics; National Bureau of Economic Research (NBER)

Date Written: April 2005

Abstract

We reanalyze data from the observational study by Connors et al. (1996) on the impact of Swan-Ganz catheterization on mortality outcomes. The Connors et al. (1996) study assumes that there are no unobserved differences between patients who are catheterized and patients who are not catheterized and finds that catheterization increases patient mortality. We instead allow for such differences between patients by implementing both the bounds of Manski (1990), which only exploits an instrumental variable, and the bounds of Shaikh and Vytlacil (2004), which exploit mild nonparametric, structural assumptions in addition to an instrumental variable. We propose and justify the use of indicators of weekday admission as an instrument for catheterization in this context. We find that in our application, the Manski (1990) bounds do not indicate whether catheterization increases or decreases mortality, whereas the Shaikh and Vytlacil (2004) bounds reveal that catheterization increases mortality at 30 days and beyond. We also extend the analysis of Shaikh and Vytlacil (2004) to exploit a further nonparametric, structural assumption -- that doctors catheterize individuals with systematically worse latent health -- and find that this assumption further narrows these bounds and strengthens our conclusions.

Suggested Citation

Bhattacharya, Jayanta and Shaikh, Azeem and Vytlacil, Edward J., Treatment Effect Bounds: An Application to Swan-Ganz Catheterization (April 2005). NBER Working Paper No. w11263. Available at SSRN: https://ssrn.com/abstract=705583

Jayanta Bhattacharya (Contact Author)

Stanford University - Center for Primary Care and Outcomes Research ( email )

Center for Health Policy
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Azeem Shaikh

Stanford University - Department of Economics ( email )

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Edward J. Vytlacil

Yale University - Department of Economics ( email )

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United States

National Bureau of Economic Research (NBER)

1050 Massachusetts Avenue
Cambridge, MA 02138
United States

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