4 ms·

That is their conclusion (which I addressed in my comment). Read the table: Table 1 says that seat belts had a non-fatal rate of 99.89% and restraint systems h

That is their conclusion (which I addressed in my comment). Read the table: Table 1 says that seat belts had a non-fatal rate of 99.89% and restraint systems had a non-fatal rate of 99.88%. They flat-out say that they had to adjust it to get those numbers: "Table 2 summarizes little difference in the unadjusted risk for death between users of child restraint systems and users of seat belts (RR, 1.03; 95% confidence interval, 0.72-1.46). After adjusting for seating position, vehicle type, model year, driver and passenger ages, and driver survival status, children in child restraint systems had a 21% reduction in risk for death compared with children in seat belts, although this difference was only marginally significant (RR, 0.79; 95% confidence interval, 0.59-1.05). After excluding the cases of serious child restraint system and seat belt misuse from FARS, children in child restraint systems had a 28% reduction in risk for death compared with children in seat belts (RR, 0.72; 95% confidence interval, 0.54-0.97)." If you read further down in their conclusions, they seem to have a real hard-on over Levitt. I am not saying that they are wrong, but the data (un-modified) supports Levitt's conclusion.

mcguire 10y ago
I presume you mean this: "In a more recent series of analyses, Levitt4 and Dubner and Levitt11 used FARS data from 1975 to 2003 and, by various methods, directly compared the mortality with child restraint systems vs seat belts in children aged 2 to 6 years and could not demonstrate a difference in effectiveness. Levitt and Porter12 restricted the FARS data set to 2-vehicle crashes in which someone in the other vehicle (ie, the vehicle without the index child occupant) died, under the assumption that the distribution of restraint use among children in potentially fatal crashes is independent of whether someone in the other vehicle dies, after adjusting for various crash-related characteristics. "The precision of these previous effectiveness estimates and their relevance to today's fleet were limited by their reliance on FARS (the limits of which were presented in the introduction), by the inclusion of older vehicles and restraints, and by failing to control for the severity (potential unsurvivability) of the crashes. Our analysis based on a modern cohort of children involved in crashes in which the car was rendered undrivable addressed many of the limitations of these previous analyses and found effectiveness estimates for child restraint systems to be greater than that for seat belts alone, with estimates greater than those of both Levitt4 and Hertz.6" Levitt, et al, used only FARS data, which only records fatal accidents. A hypothetical accident where only the child would have died but that was prevented by the restraints would therefore not show up in the data, leading to the value of the restraints being under reported. Further, failing to control for the severity of the accident (which this work does using the survival of the driver) also undervalues restraints: if the car ends up as a ball the size of a grapefruit, it doesn't matter what restraints were used.
- mhuffman 10y ago
  Correct. > Levitt, et al, used only FARS data, which only records fatal accidents. A hypothetical accident where only the child would have died but that was prevented by the restraints would therefore not show up in the data, leading to the value of the restraints being under reported. This is the same regarding any type of restraints, including seat belts, no? Also, you should realized that all of their extrapolated data is also hypothetical, and relies on spotty reporting from police. Please note, that I am not convinced that Levitt has it right, just that he is not incorrect regarding the data.

mcguire 10y ago

I presume you mean this: "In a more recent series of analyses, Levitt4 and Dubner and Levitt11 used FARS data from 1975 to 2003 and, by various methods, directly compared the mortality with child restraint systems vs seat belts in children aged 2 to 6 years and could not demonstrate a difference in effectiveness. Levitt and Porter12 restricted the FARS data set to 2-vehicle crashes in which someone in the other vehicle (ie, the vehicle without the index child occupant) died, under the assumption that the distribution of restraint use among children in potentially fatal crashes is independent of whether someone in the other vehicle dies, after adjusting for various crash-related characteristics. "The precision of these previous effectiveness estimates and their relevance to today's fleet were limited by their reliance on FARS (the limits of which were presented in the introduction), by the inclusion of older vehicles and restraints, and by failing to control for the severity (potential unsurvivability) of the crashes. Our analysis based on a modern cohort of children involved in crashes in which the car was rendered undrivable addressed many of the limitations of these previous analyses and found effectiveness estimates for child restraint systems to be greater than that for seat belts alone, with estimates greater than those of both Levitt4 and Hertz.6" Levitt, et al, used only FARS data, which only records fatal accidents. A hypothetical accident where only the child would have died but that was prevented by the restraints would therefore not show up in the data, leading to the value of the restraints being under reported. Further, failing to control for the severity of the accident (which this work does using the survival of the driver) also undervalues restraints: if the car ends up as a ball the size of a grapefruit, it doesn't matter what restraints were used.

mhuffman 10y ago
Correct. > Levitt, et al, used only FARS data, which only records fatal accidents. A hypothetical accident where only the child would have died but that was prevented by the restraints would therefore not show up in the data, leading to the value of the restraints being under reported. This is the same regarding any type of restraints, including seat belts, no? Also, you should realized that all of their extrapolated data is also hypothetical, and relies on spotty reporting from police. Please note, that I am not convinced that Levitt has it right, just that he is not incorrect regarding the data.