Cherry Picking Data To Prove Your Point

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The more I see of the world the more it strikes me that people want more science, rather than less, and that they want to use it in odd ways: to abrogate responsibility, validate a hunch, or render a political or cultural prejudice in deceptively objective terms. As long as you cherry pick the data and keep one eye half closed, you can prove anything with science.

Last week's Independent on Sunday splashed with the headline: Cannabis - An Apology. It went on: "In 1997 this newspaper launched a campaign to decriminalise the drug. If only we had known then what we can reveal today ... record numbers of teenagers are requiring drug treatment as a result of smoking skunk, the highly potent cannabis strain that is 25 times stronger than resin sold a decade ago."

Twice in this story cannabis is said to be 25 times stronger than it was a decade ago. For Rosie Boycott, in her melodramatic recantation, skunk is "30 times stronger". In one inside feature the strength issue is briefly downgraded to a "can". It's even referenced. "The Forensic Science Service says that in the early nineties cannabis would contain around 1% tetrahydrocannabidinol (THC), the mind-altering compound, but can now have up to 25%."

Well I've got the Forensic Science Service data right here, and the earlier data from the Laboratory of the Government Chemist, the UN Drug Control Programme, and the EU's Monitoring Centre for Drugs and Drug Addiction. I think that people are well able to make their own minds up when given true facts.

The LGC data on mean potency goes from 1975 to 1989. Resin pootles around between 6% and 10% THC, herbal between 4% and 6%, with no clear trend. The Forensic Science Service data takes over to produce more modern figures, showing not much change in resin, and domestically produced indoor herbal cannabis doubling in strength to between 12% and 14%.

The rising trend of cannabis potency is gradual, and driven largely by the increased availability of intensively UK grown indoor herbal cannabis. You could argue that intensive indoor cultivation of a plant that is easy to cultivate outdoors is the cannabis industry's reaction to illegality. It is dangerous to import in large amounts, dangerous to be caught growing a field of it. So perhaps it makes more sense to grow it intensively indoors, producing a more concentrated product. There is little incentive to produce a perversely strong skunk product for the mass market, since most people tend not to pay any more for unusually strong skunk.

There is exceptionally strong cannabis to be found in some parts of the UK market today: but there always has been. The UN Drug Control Programme has detailed vintage data for the UK online. In 1975 the LGC analysed 50 seized samples of herbal cannabis: 10 were from Thailand, with an average potency of 7.8%, the highest 17%. In 1975 they analysed 11 samples of seized resin, six from Morocco, average strength 9%, with a range from 4% to 16%.

To get their scare figure, the Independent compared the worst cannabis from the past with the best cannabis of today. But you could have cooked the books the same way 30 years ago: in 1975 the weakest herbal cannabis analysed was 0.2%; in 1978 the strongest was 12%. Oh my god: in just three years herbal cannabis has become 60 times stronger. This scare isn't new. In the US, in the mid 1980s, during Reagan's "war on drugs", it was claimed that cannabis was 14 times stronger than in 1970.



News Hawk- User http://www.420magazine.com/
Source: Guardian News
Author: Ben Goldacre
Contact: badscience@guardian.co.uk
Copyright: Guardian News and Media Limited
Website: Cherry picking data to prove a point about cannabis