PCC rules on depressed zero
The complaint made by Straight Statistics reader John Huggins to the Press Complaints Commission against The Guardian has been rejected.
Mr Huggins complained that a graph on page 1 of The Guardian on August 13 misrepresented youth unemployment by curtailing the vertical axis. This exaggerated the change in unemployment rates, at first glance implying they had risen six-fold.
Graphs with a “depressed zero” are commonplace, and to some – clearly including Mr Huggins – reprehensible. But the PCC takes the view that so long as the vertical axis is clearly marked, as it was in this case, the reader is not misled. So the PCC code on accuracy was not breached, it has ruled.
Mr Huggins is unpersuaded. He agrees that numerate readers would take the trouble to read the axes in order to interpret the chart, but that these are the very readers who would have no need of a chart anyway. Those who are not very numerate and need a chart would have got a very misleading view, he says, appealing to the PCC to think again.

Nick Howell (not verified) wrote,
Tue, 22/09/2009 - 08:02
Oh dear....I thought I was reasonably numerate but I have no idea what a "depressed zero" is or the effect that it would have on my visual interpretation of a graph!
Alan Cleaver (not verified) wrote,
Tue, 22/09/2009 - 10:50
This 'trick' with graphs to exagerrate a particular viewpoint seems to be getting more and more common. Sometimes it is deliberate to sway readers but I suspect on many other occasions it's just because the person doesn't know how to draw a graph properly. Some programs like Excel seem to start the vertical axis wherever it likes - one would hope it would default to zero.
Alex (not verified) wrote,
Wed, 23/09/2009 - 21:30
"these are the very readers who would have no need of a chart anyway"
So numerate people don't need graphs then? So why do scientists produce work with so many of them?
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