October 2, 2012

Fishy journalism

By comparison with NZ, the UK media are a target-rich environment for statistical and scientific criticism.  The Telegraph ran a headline “Just 100 cod left in North Sea”, and similar stories popped up across the political spectrum from the Sun to the Socialist Worker.

The North Sea, for those of you who haven’t seen it, is quite big. It’s about three times the size of New Zealand.  You’d have a really hard time distinguishing 100 cod in the North Sea from no cod.  An additional sign that something might be wrong comes later on in the Telegraph story, where they say

Scientists have appealed for a reduction in the cod quote from the North Sea down to 25,600 tons next year.

If there are only 100 cod, they must be pretty big to add up to 25,600 tons of catch. They’re not only rarer than whales, they are much bigger.

It turns out (explains the BBC news magazine) that the figure of 100 was for cod over 13 years old. The papers assumed that 13 was some basic adult age, but they should have been thinking in dog years rather than human years.  A 13-year old cod isn’t listening to boy bands, it’s getting free public transport and looking forward to a telegram from the Queen.

The government department responsible for the original figures issued an update, clarifying that the number of adult cod in the North Sea was actually about 21 million.


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 »