other firm padding (such as a pool noodle) under the base near the point where the back and bottom of the vehicle seat meet." Safety seats come with an instruction booklet with additional information on the appropriate angle for the seat. Criticism There has been some criticism of the safety standards for forward-facing child safety seats, in particular by the economist Steven D. Levitt, author of the popular book Freakonomics, who evaluated only fatal collisions between 1975 and 2003. Other researchers say that child safety seats offer a considerable safety advantage over seat belts alone, when looking at data about collisions in newer cars with newer child safety seats, without restricting the data to include only fatalities. Child safety seats can be expensive and bulky, and if the family has multiple children who need to use child safety seats at the same time, it may even be necessary to buy a larger vehicle or specialized, narrower safety seats to comply with legal requirements about transporting children safely. One economic study found that these requirements affected families' decisions about birth spacing, and estimated that, in 2017, the requirements for fitting multiple child safety seats into a vehicle at the same time had likely discouraged several thousand families from having an additional child at that time. A major challenge to child restraint use is that it is considered as a mechanism to discipline children instead of being seen as a safety device by parents and as children became older they actively seek opportunities to negotiate the non-usage of restraints. See also BeSeatSmart Child Passenger Safety Program National Child Passenger Safety Board Bike child seat Seat belt Child Passenger Safety Week References External links Safercar.gov For information on child restraint use in the U.S. 2007 RTA/NRMA/RACV (Australian) Crash Test Results National Child Passenger Safety Board: Standardized curriculum used to train and certify child passenger safety technicians and instructor Seat Road safety