P value falls, use also falls
An interesting report in the Herald yesterday on methamphetamine use. A forthcoming Health Ministry survey apparently shows a decrease in the proportion who report using P over the past year, from 2.1% in 2007/2008 to 1% now (yes, that will be larger than the margin of error; it’s a big survey).
On the other hand, an ongoing Massey University study that interviews police detainees about drug and alcohol use finds that the street price and availability of P have not really changed.
This evidence of a decrease on the demand side is encouraging for two reasons. First, it suggests a decrease in the number of people who are dumb enough to want to take methamphetamine, which has to be progress. Second, it suggests that the pseudoephedrine ban wasn’t responsible, as that should have acted on the supply side by driving up street prices. Can we have our Sudafed back?
Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »
And can we please have our ephedrine unlocked again in operating theatres, rather than locked away requiring two signatures. Because that’s vaguely dangerous for an emergency drug.
12 years ago
Ephedrine is an emergency drug? What’s it used for that you couldn’t just use epinephrine for?
12 years ago
You can use adrenaline (i know one anaesthetist who does this) but it tends to give a more profound response than ephedrine. More profound can mean cardiac ischaemia in
susceptible patients and lead to significant problems. Basically adrenaline is slightly more difficult / risky to titrate.
12 years ago
Thanks. Interesting to know.
12 years ago
Sorry to disappont —
If demand has fallen and price has not, then that indicates an additional shift of the supply curve. That suggests that the pseudo-e ban has been partially effective, maintaining a higher P price in the face of falling demand.
But I agree about Sudafed.
12 years ago
Well, the price has actually fallen about 10% in real terms since 2010…
12 years ago
Let’s take those numbers:
fall in quantity ~ 50%
fall in price ~ 10%
Assuming no supply shift, supply elasticity = 50/10 = 5.
Wikipedia (Price_elasticity_of_supply) gives a supply elasticity for tobacco of 7.0, but conventional products are much lower (1.0 to 2.0, mainly).
So, hard to say, really. The Sudafed ban may or may not have been a factor. Maybe I can get a grant to estimate the actual price elasticity of supply for illegal drugs in NZ?
12 years ago
A 50% fall in the proportion of the population that use P is not the same as a 50% fall in the demand for P, since the marginal user is likely to be more casual about their usage.
In case you want to attempt to disintangle the supply and demand effects, here’s a recent study focused on New South Wales, which found a price elasticity of demand for methamphetamine of -1.8: http://www.bocsar.nsw.gov.au/lawlink/bocsar/ll_bocsar.nsf/vwFiles/CJB134.pdf/$file/CJB134.pdf
12 years ago
I had to read this post twice before I realised it wasn’t about frequentist hypothesis testing.
12 years ago
Just of one the language differences you’ll have to get used to in NZ
12 years ago