One of the (few) specific claims Melanie Phillips made about drugs on the Moral Maze was that "75% of parents who kill their children are cocaine users". Now, apart from what I call the "Ribena effect" (their advertising claims that 98% of British blackberries are used to make Ribena in a way that implies that Ribena is 98% blackberries. It's not), there are so many qualifiers that you'd need to add to this statement to make it meaningful:
1. Just how many parents have killed their children in the UK in the last, ooh, 50 years? If it's less than about 1000, then I'd say that you'd need to put some pretty big confidence intervals around your 75% claim.
2. What proportion of cocaine users who are parents kill their children? If it's <0.1%, I imagine that it's starting to look comparable to rock climbing, road accidents, etc in terms of risk.
3. Does the number of parents killing their children over the last fifty years correlate with cocaine usage over the last fifty years?
4. Is it a particular kind of cocaine? Crack?
5. Is it a particular kind of user? An addict taking *much per week?
I realize that I shouldn't get so angry over someone who is so obviously an idiot. But she seems to embody everything that's wrong with the popular press that it's hard not to be angry that she gets to express her views in print to hundreds of thousands (millions?) of readers and attempt to sway them. Bah.