The 1997 Census of Manufactures reported that consumers in the U.S. spend over $300 million on roughly four million child safety  seats each year. Meanwhile, it is estimated that 80% of child safety seats are incorrectly installed (US DOT, 1996), reducing the safety benefits provided by child safety seats (Kahane, 1986).

Seat belts offer a low-cost alternative to restrain children. All modern passenger vehicles come equipped with seat belts. Thus, there is no marginal cost to the consumer associated with their use. On the other hand, seat belts are primarily designed to fit adult passengers.

Shoulder belts may fall improperly across the child’s neck, and the lap belt may lie on the child’s abdomen rather than across the hips, leading to possible abdominal injury and what is known as “seat belt syndrome”.

In spite of these important drawbacks of seat belts for children, previous research has documented that children restrained by seat belts fare much better in crashes than unrestrained children (Partyka, 1988; Johnston, Rivara, and Soderberg, 1994; Hertz, 1996). See, for example, Kulowski and Rost, 1956; Garrett and Braunstein, 1962; Agran, Dunkle, and Winn, 1987; Winston et al., 2000; Durbin, Arbogast, and Moll, 2001; and Arbogast et al. 2002.

There is a surprisingly limited body of research assessing the relative efficacy of child safety seats and seat belts, and the existing studies come to very different conclusions.

In a series of papers utilizing a large sample of parental reports of injuries among children aged 4-7, belt-positioning booster seats (the dominant form of child safety seat for this age group) have been found to reduce significant injuries by approximately 60% relative to seat belts (Winston et al., 2000; Durbin et al., 2003).

Levitt (2005) utilizes police report data for crashes with at least one fatality and finds no statistically significant difference in fatalities or injuries between child safety seats and lap-and-shoulder belts for children in this age range.2 That data set is far from ideal for studying injuries, however, as less than 2% of crashes with injuries involve a fatality.

In this paper, we undertake the first comparison of the effectiveness of child safety seats and seat belts based on representative samples of all crashes reported to the police.

We utilize three different data sets: (1) the General Estimates Survey (GES), a nationally representative sample of approximately 50,000 crashes each year for sixteen years; (2) New Jersey Department of Transportation (NJDOT) data covering all crashes in that state between 2001 and 2004, and (3) a Wisconsin data set that not only includes the universe of crashes with police reports in that state from 1994 to 2002, but also links these crashes to hospital discharge records.

Using these data, we are able to exploit the wealth of information in police reports, as well as within-vehicle and within-accident variation in restraint use, to compare seat belts and child safety seats in preventing injury.

The results suggest that lap-and-shoulder seat belts perform as well as child safety seats in preventing serious injury for children aged 2  through 6. Safety seats are associated to Elliot et al.

(2006), which combines the fatal accident data with another data set, the National Highway Traffic Safety Administration’s National Automotive Sampling System Crashworthiness Data System, challenges the Levitt (2005) conclusions. With a statistically significant reduction in the least serious injury category.

According to our estimates, if every child wearing a lap-and shoulder seat belt had instead been in a child safety seat, the number of injuries in this least serious category would be reduced by roughly 25%.

Lap belts are somewhat less effective than the two other types of restraints, but far superior to riding unrestrained. The structure of the paper is as follows.

Section two describes the data sources and provides some summary statistics. Section three describes the empirical strategy and main results. Section four offers some conclusions and interprets the results in terms of the estimated benefits of injury reduction compared to the costs of increased safety seat use.