Nov 012009
 

It is now clear that the UK’s Advisory Council on the Misuse of Drugs is in danger of disintegration as additional members seem to be considering (or have) resigned in protest at the sacking of Professor Nutt and the seemingly arbitrary decisions made by the Government on the use of recreational drug use.  There has long been a suspicion that the Government’s (all UK governments and not just the most recent one!) decisions on which drugs should be legal and which ones illegal, is based more on which ones are acceptable to the establishment and which ones are not.

The UK’s system of drugs laws is based around three classes of drugs (A, B, and C) with a decreasing scale of punishments for misuse from the harshest for the use of the most harmful drugs (class A) to the lightest punishment for the least harmful (class C). Or rather it should be.

Both the classification of Ecstasy (as class A) and the re-classification of cannabis (from C to B) were made by ignoring the scientific advice and paying more attention to media hysteria. Both are classified higher than the risk of taking them justifies. What other drugs have been classified inappropriately?

If the government wants to make arbitrary decisions on drugs classifications, they need to get honest and get rid of the whole classification system. And they need to stop taking advice from scientists – taking advice and then ignoring it wastes a great deal of time on those who formulate the advice, and if the advice is ignored there is no point in getting it.

Alternatively, the government needs to accept the advice of the experts and get the politicians out of the loop. Even to go so far as to include legal drugs into the classification system. For instance why are not alcohol and tobacco not classified appropriately ? They could be classified according to their harm with a special note that they are legal for practical reasons.

Over the weekend, the criticisms of Professor Nutt can be split into two.

The first criticism is that he shouldn’t have said what he said as a government advisor. Well I’m sure Professor Nutt knows this, knew he would be sacked for saying what he said, and felt that he had to say it anyway. He has certainly managed to ignite a debate on the subject.

The second criticism is that he is wrong that drugs such as cannabis are less harmful than the drugs they are classified with. First of all Professor Nutt was not saying that cannabis is harmless; he was saying that it’s harm does not justify it being classified as class B (it should be C instead). Secondly those criticising him seem to think that their personal (bad) experience with cannabis invalidates the scientific evidence.

Nothing could be further from the truth. Scientific evidence (on drug use) is about moving beyond personal experience both good and bad, and getting to the truth on the level of risk. There are many who would claim that cannabis is harmless because it hasn’t caused them any harm (man), and some who would claim it is very harmful because it has harmed them. Both are wrong – cannabis is harmful, but the amount of harm considering the number of users is very low.

As an analogy, the use of aspirin can cause stomach ulcers, stomach bleeding, and tinnitus. Rather extreme for curing a little headache! Perhaps aspirin should be banned ? Of course not – the benefit far outweighs the risk.

In an ideal world, the current fuss over Professor Nutt’s lecture and drugs policy will result in seeing some sanity in drug prohibition – perhaps even we would see the legalisation of drugs (prohibition probably causes far more harm to society as a whole than the harm resulting from drug use). However it is more likely that we will see more gross stupidity.

Apr 182008
 

I recently discovered one of the most entertaining web reads I’ve come across for ages … Bad Science which is a site dedicated to pointing out where the (mostly media) uses “Bad Science” or falls victim to “Bad Science”. The author (Ben Goldacre) is a medical doctor so most of the criticisms are in relation to medicine rather than science in general. But the debunking of rubbish media reports on (mostly) medical issues is worthwhile and done in an entertaining way.

It is interesting that many of the more foolish reports in the media have to do with bad statistics rather than bad science itself. That is I suppose not too surprising, as statistics seems to be widely misunderstood.

I have the advantage that many years ago I spent some time studying statistics, and many media reports have the effect of making my inner statistician jump up and down in fury shouting “Bullshit” over and over again. Fortunately he doesn’t shout too loudly or I’d run the risk of being shut away in a room with nice soft walls.

Statistics don’t lie, but they don’t always say what we think they do

I’m going to make use of an example relating to cannabis and an article publish by that paragon of excellent and accurate reporting, the Daily Mail. The article itself is here … scary isn’t it?

A report that has statistics that says that people who smoke cannabis have a 41% higher risk of schizophrenia, indicates that cannabis smokers are more likely to have schizophrenia than the general population. That doesn’t mean that cannabis causes mental health issues; that is an untested hypothesis. A quick uneducated guess at a number of possible reasons why includes :-

  • Cannabis use increases the risk of mental health problems (yes it is possible).
  • People with mental health problems are more likely to use cannabis than others.
  • Cannabis use makes existing mental health problems worse.
  • There is no link between cannabis use and mental health problems; the correlation is accidental.
  • The study that found a correlation between cannabis use and mental health problems is flawed and there is in fact no such correlation.

One of the biggest mistakes anyone can make with statistics is to take a link between two variables (a correlation) and assume that one variable causes another (cannabis use causes mental health issues). This is known as “Correlation does not imply causation”; stealing a Wikipedia example, there is a correlation between going to bed with shoes on and waking up with a headache. Sleeping with shoes on does not cause headaches, but drinking copious quantities of alcohol makes it more likely that you will sleep with your shoes on, and far more likely you will wake with a headache.