Funny you should mention this....a few years ago I had a bad crash, patrol came and offered a sled ride down and to take x-rays. I refused stating that I will be alright. I filled out a card stating that I turned down further aid. I would later find out that I had broken my back and thumb even though with much pain I was able to ski down ungear and get in a car.
I think what I am tryijg to get at besides the sample bias and anectdotal evidence is that when we see so many getting taken off the hill, each case is special and important. A statistical analysis of many occurances in a population is for use by insurance companies, maybe those charged with staffing patrollers during peak times or police staffing in big cities or such.
To say that the incidence of serious accident or that the number deaths while skiing is low, is incidental to the actual few who do get injured. And when you consider that many are probably avoidable accidents, safety development on the slopes is important.
Ski industry would have us believe that sking is safe and I have spoken with patrollers who are told to not be tough on minor infractions because we are all just trying to have fun. Yet every time I go out I see plenty of folks getting taken off the hill by patrol. Of these who are taken off, only a proportion of them would be considered serious. But to the kid or mother or father in the sled, the injury is serious.
Of course many many more ski without serious accident but it is the injuries that are important not the uninjured. So proportion and ratio is something that has an application which may be over used or misused.
And referring to sample bias, when a guy hits his head and is temporarily dizzed enough to need help off the hill, many of them are ok by the tme they get to the bottom. In this case, the required paperwork would show that the injury was not serious...so the kid may have had a consussion that was not serious. And it gets recorded in the non serious column. If I stretch my MCL and walk away or ski away and go home without help or even with help, is that serious?
And isnt the diagnosis done after the person has left the resort? Isnt the actual diagnosis actually done days later after the MRIs, after the surgical consult? after a plane ride away from the resort?
I would say that every injury on the hill is serious. Seemingly innocuous injuries are often later found to effect the daily activities of many with orthopedic injuries. And this is why you get the neck brace on every single sled ride administered around the world.