Originally Posted by wphamilton

I have seen of a number of them, that measure helmet use in general. Unless wearing the equipment makes one less likely or more likely to be involved in an accident, the numbers are the same. If it makes one slightly more or less likely, as has been suggested, the numbers will be slightly different.

Even if no one ever provided a clue about it was a valid objection, it remains to be seen how it calls into question this study's methodology or conclusions.