Sample Selection in the Estimation of Air Bag and Seat Belt Effectiveness

42 Pages Posted: 10 Feb 2000 Last revised: 15 Sep 2022

See all articles by Steven D. Levitt

Steven D. Levitt

University of Chicago; National Bureau of Economic Research (NBER); American Bar Foundation

Jack Porter

affiliation not provided to SSRN

Date Written: July 1999

Abstract

Measurement of seat belt and air bag effectiveness is complicated by the fact that systematic data are collected only for crashes in which a fatality occurs. These data suffer from sample selection since seat belt and air bag usage influences survival rates which in turn determine whether a crash is included in the sample. Past researchers either ignored sample selection or adopted indirect estimation methods subject to other important biases. We propose a simple, but novel, solution to the selection problem: limiting the sample to crashes in which someone in a different vehicle dies. Under relatively weak conditions, consistent estimates can be obtained from this restricted sample. Empirically, we find seat belts to be more effective in saving lives than most previous estimates. Air bags, however, appear to be less effective than generally thought. If our coefficients can be generalized to all crashes, the cost per life saved with seat belts is approximately $30,000, compared to $1.6 million for air bags.

Suggested Citation

Levitt, Steven D. and Porter, Jack, Sample Selection in the Estimation of Air Bag and Seat Belt Effectiveness (July 1999). NBER Working Paper No. w7210, Available at SSRN: https://ssrn.com/abstract=203149

Steven D. Levitt (Contact Author)

University of Chicago ( email )

1126 East 59th Street
Chicago, IL 60637
United States
773-834-1862 (Phone)
773-702-8490 (Fax)

National Bureau of Economic Research (NBER)

1050 Massachusetts Avenue
Cambridge, MA 02138
United States

American Bar Foundation

750 N. Lake Shore Drive
Chicago, IL 60611
United States

Jack Porter

affiliation not provided to SSRN

Do you have a job opening that you would like to promote on SSRN?

Paper statistics

Downloads
85
Abstract Views
2,626
Rank
553,944
PlumX Metrics