It's an economist who co-wrote the book (thus no bias is intended or created) and what he did was compare a bunch of data on car seats crashes with and without car seats and this is what he came up with:
Children, older than age 2, are just as safe with a regular seat belt as they are in a car seat.
And then, the authors went and conducted their own children's seat belt safety test. But first they had to find a crash test place that would let them do the test (apparently, most of the crash test places are in cahoots with the car seat manufacturers so none of them wanted to do it). They finally found one who would do it for them (under the conditions of curiosity and anonymity on their end) and they again found that seat belts were just as safe.
So why are we all putting our kids in car seats? (And, yes, I still do, because I am required to by law... so don't go getting your panties in a knot people. But the minute my daughter turns 8 or grows taller than 4'9", she is getting out of that booster seat.)
