Effects of child restraint laws on traffic fatalities in eleven states.

Mandatory child restraint laws in 11 states were evaluated for their effect on motor vehicle fatality rates among young children. Data from 1976 through 1983 were analyzed using a monthly time-series design involving 54 months' pre-law and 12 months' post-law data. The 11 states collectively had a mean of 8.8 and a standard deviation of 3.6 fatalities per month among young children. Such small frequency counts resulted in a large proportion of the variation being random. Statistical power analyses found fatality reductions of 20% to 25% following the child restraint laws would be statistically significant. Reductions of such a magnitude were not found for young children. Based on these findings, we recommend that evaluations of highway safety policies focusing on a specific age group within a single state not be limited to analyses of traffic fatalities alone. Studies employing analyses of the larger numbers of crash-induced injuries have identified modest but important casualty reductions not found when analyzing fatalities alone.