Seat belts are a simple technology; they have saved many lives since their introduction in the 1950s. Since then, however, concern over protecting children in traffic accidents has led to many models of child car seats, and many state laws requiring parents to put kids in them until they are six or seven years old. In "SuperFreakonomics," Stephen Dubner and Steven Levitt compare the safety record of car seats and seat belts, going so far as to buy their own testing time at a safety rating facility. Their analysis brings into question whether seat belts actually perform any worse than newer technologies. Some people, including the Secretary of Transportation, are questioning these results. Here is "Super Freakonomics" co-author Steven Levitt's response.