I'm seriously perplexed by your continuing insistance that I define a secondhand injury. How much more clear are you looking for me to be? Can you give me an example of situations that, from what I've described, it is unclear whether or not it would qualify as a secondhand injury?
Yes. I've given numerous examples of things that could qualify as "secondary injury", and yet are all very very different things.
All I'm looking for is a comparison rate of the injuries of people in accidents based on the seatbelt use of other people in the accidents.
As an example: "Among those in automobile accidents, those wearing seatbelts were 45% less likely to suffer serious injuries." These are the sort of statistics used all the time to prove the firsthand effectiveness of safety belts.
What I'm looking for is something like this: "Controlling for their own seatbelt use, all passengers in vehicles with buckled-in drivers were 20% less likely to suffer serious injuries from an accident."
Or something like this: "Controlling for their own seatbelt use, people in accidents with another vehicle were 31% less likely to suffer serious injuries if the driver of the other vehicle was wearing a seatbelt".
Those are the sort of claims that I believe are being made without concrete evidence to back them up, and that's the sort of evidence I want to see to back those claims up.
You're asking for rather interesting statistics. You do realize that controlled studies cannot be carried out on these subjects, right? That the numbers being quoted to you are numbers based upon after the fact analysis of real life accident data, and rely heavily upon self reporting of whether or not a seatbelt was being worn, right? That the vast majority of accidents aren't investigated by professional accident analysis specialists, and that scientists are working off of injury report databases and FARS information to come up with their numbers?
Do you understand that even those numbers being quoted for car crash injury and fatality due to lack of seat belt use are not "hard numbers" but are instead estimations based on past data?
Or that when you see numbers about "45% of serious injuries in car accidents could be avoided by seat belt use", that 45% INCLUDES secondary injury?
I also don't think you understand that secondary injuries being avoided by seatbelt use is not a matter of necessary statistics. It is a matter of the physics of a car crash.
There are three forms of collision during a car accident.
1) The vehicle's collision
2) The human collision
3) Internal collision
The human collision aspect of a crash includes something called "person-to-person impact".
Information on person-to-person impact:
http://floridadrivers.com/safety-belt-use-fact-sheet.html
Another form of human collision is the person-to-person impact. Many serious injuries are caused by unbelted occupants colliding with eachother. In a crash, occupants tend to move toward the point of impact, not away from it. People in the front seat are often struck by unbelted rear-seat passengers who have become high-speed projectiles.
http://www.arizonadriver.com/course_sample.html?p=5
There is also great potential for person-to-person impact. In a crash, occupants tend to move toward the point of impact, not away from it. People in the front seat are often struck by unbelted rear-seat passengers who have become high-speed projectiles. Many serious injuries result from the human collision.
I can quote about 50 other sources for this information, but they all say pretty much the same thing.
Wearing a seatbelt prevents the "human collision" aspect of an accident from happening. This, in and of itself, demonstrates that wearing seat belts reduces secondary injury.