Send to

Choose Destination
Stat Interface. 2009;2(4):437-447. doi: 10.4310/SII.2009.v2.n4.a5.

A propensity score approach to estimating child restraint effectiveness in preventing mortality.

Author information

Department of Biostatistics, University of Michigan School of Public Health, M4041, SPH II, 1420 Washington Heights, Ann Arbor, MI 48109, USA.
TraumaLink Injury Research Center, The Children's Hospital of Philadelphia, Division of Emergency Medicine, Department of Pediatrics Center for Clinical Epidemiology and Biostatistics University of Pennsylvania.
TraumaLink Injury Research Center The Children's Hospital of Philadelphia, Division of General Pediatrics, Department of Pediatrics Leonard Davis Institute for Health Economics University of Pennsylvania.


Confounding between the child's restraint use and driver behavior can bias restraint effectiveness estimates away from the null if survivable crashes are more common in certain restraint types. Analyzing only fatal crashes may introduce selection bias toward the null because any protective effects of a restraint type will underrepresent children in that restraint. A marginal-structural-model-type estimator suggests a 17% reduction in fatality risk for children aged 2 through 6 in child restraint systems relative to seat belts. This reduction is estimated at 22% when severe misuse of the restraint is excluded.


Child safety seat; Confounding; Fatality; Injury epidemiology; Marginal structural model; Selection bias

Supplemental Content

Full text links

Icon for PubMed Central
Loading ...
Support Center