This is again where the helmet research is biased and almost devious.
Like a seatbelt a helmet is an ornament or accessory with absolutely no function at all
... until an accident occurs when you can ask whether it played a part in reducing an injury
Cohort studies then show ALL the head injuries, and it is only in these cases that asking the question about the efficacy of the helmet is possible
However the researchers know that any "evidence" will also show that helmets will hava a similar effect on all head injuries. But politically there will be an outcry if they suggest that all these head injuries were preventable
So they then exclude the vast majority of head injuries and make claims only for a small group wher ethere is a political agenda in their favour
Lets give a similar example:
Why do you have soles on your shoes?
Is this sensible?
I look at shoes with soles on and decide that they might have some benefit
So I take a group of five year olds and research the use of shoes walking to school
I find that soles on shoes are an effective and comfortable way of preventing cuts and minor injuries
However I then refuse to consider that the same benefit could be acheived if six year olds wore shoes with soles...or that the five yearolds wore these shoes when walking to the shops
SIx year olds wearing shoes, or five year olds wearingthem whn walking to the shop is then something that becomes unacceptable and avoided
Not really sensible yet we acept this ludicrous situation with helmets!