There's lies, damned lies and....

Suppose you have two activities, A and B, each of which carries a 1% chance of harm - in other words about one in every hundred people who engage in these activities is likely to come to grief.  Now suppose that a million people engage in activity A, whereas only 20,000 people take part in activity B.  Statistics will indicate that some 10,000 people have come to harm as a result of activity A, and about 200 from taking part in activity B.  Presented with just these figures you might come to the conclusion that activity A is far more dangerous than activity B, whereas, as we have seen, the risk associated with them is identical.  I haven't read Professor Nutt's report on the comparative harm caused by alcohol and various other drugs, but certainly as reported in the press, he seems to be saying that because far more people end up in A & E or at the doctor's or in hospital or dead as a result of drinking alcohol than do as a result of taking heroin or other drugs, that alcohol is more dangerous than these other drugs.  But of course, it is exactly what you would expect - given that both drinking alcohol and taking drugs carries a risk to health, the fact that far more people drink alcohol than take drugs means it is inevitable that more people will cause damage to their health by drinking the former than taking the latter.  It may be that Professor Nutt covers this point in his report, but if not, it's a basic statistical error.