While I believe Pot can make a schizophrenic more schizophrenic, I'm not sure it cause life long schizophrenia. On the other hand a boderline case will get worse; I have no doubt.I think the original post shows one thing and one thing only - Statistics can be produced to support any point you want.
You need to remember that yes 13 people died playing high school football. However, what portion of these were attributed to poor and\or incorrect use of safety equipment and pre-existing medical conditions?
How many of these deaths were actually due to the fact that they were playing football and how many were due to other factors??
There is one thing that is true. Sport is good for you. Perhaps there are things that could make sport, and in this case High School Footbaly, safer but no one can argue that children that participate in sport are not healthier than those who don't.
The pot comments i believe are also incorrect. It does not take into account the number of people who have died from lung cancer caused by smoking (in this case pot). It does not take into account the number of people who develop schizophrenia as a result of pot use and either end up in a mental hospital for the rest of their lives or end up commiting suicide.
All drugs have side effect - even the pain killers we commonly use. The difference between controlled drugs (that you get at a chemist etc) and those that are currently illegal (pot, coke, ice etc) is that the side effects of the illegal ones are extremely harmful to the human body and also cause behaviour that is harmful to others or to the user.
At the end of the day the original post is just a use of statistics to prove a point. Any high school student would be able to do such manipulation. Plus 70% of statistics are made up anyway - 45% of people know that!!
Sean