Originally Posted by
invisiblehand
I just want to write that there are sound studies. That is, the researchers do what they can with the data. The data, however, often cannot support the strong statements that we want to make without modeling assumptions.
That's true, but I think it's much more important than merely wanting to make strong statements - it's about wanting to ride bikes safely and effectively, and not wanting others to be dissuaded from doing so based on false notions about what is or is not safe and effective.