In More or Less this week we looked beyond reports of more drug testing in schools and the workplace (the prime minister has spoken approvingly of tests in schools), to the products advertised for on-site drug testing.
Despite high detection rates, drug testing can produce false results
How good is 99% reliability? It depends what you're measuring. If it's airline flights, you would not be remotely happy. But what about drug tests?
According to the regulatory body which tests these kits, the Medicines and Healthcare products Regulatory Agency (MHRA), they are classified as performing well if they produce an accurate result 97% of the time.
We found one for sale on the web saying it achieved 95 - 97% accuracy.
How good is that if you want to screen, say, a secondary school of 1000 pupils?
The answer is that it would produce between about 30 and 50 results which either falsely suggested drug use or falsely cleared someone who was taking them.
BBC Radio 4's More or Less was broadcast on Thursday, 8th July, 1500 BST
The MHRA says such tests should not be used as the basis for action, only as a prompt for a further - and much more rigorous - lab test.
We also reported on the baseball team that went from no-hopers to contenders with the help of a heavy dose of statistics.
And on the instinct to see cause and effect, as in the correlation reported last week between mobile phone use and infertility in men.
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Producer: Michael Blastland
Editor: Nicola Meyrick
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