I used to drink and drive all the time (I'm a recovering alcoholic). I never got a ticket for it, or got in an accident. Should I conclude that my experience makes it OK? Or was I just f***ing lucky? Which one of us (Sober Jeff T or drunk Jeff T) do you want to share the road with?
My father was a well-known cancer researcher (look up E. Donnall Thomas). He considered statistical analysis to be the only reliable way to track medical results. The Fred Hutchinson Cancer Center, where he worked keeps track of every patient from the moment they start treatment until the day they die. It is the only reliable way to measure the results of their work.