A Straight Statistics reader, John Huggins, has taken exception to a graphic in The Guardian, illustrating the rise in youth unemployment.

The graphic (below) which appeared on the front page on August 13, is a good example of the “depressed zero”, a standard technique for making any change look more dramatic. The vertical scale has been truncated so that it starts not at zero, but at 9 per cent. This makes the rise to the current level of more than 17 per cent look positively vertiginous.
 
Mr Huggins believes this very common technique to be a gross distortion of the facts. He’s taken his objection to the Press Complaints Commission, saying: “A glance at the picture, which is all the majority of people would do, would give the impression that the rate of unemployment of young people was now six times the rate at its lowest point. In fact, the current rate around 17% is less than double the lowest rate of around 10%.”
           
             
 
Who’s right? A graph that starts at zero keeps visual proportions in line with numerical proportions, so it’s certainly more honest. But graphs are usually drawn to show differences, since the change is what the story is about. For that purpose, a truncated scale may be acceptable, so long as it is clearly labelled - as the Guardian’s is.
 
This is the form taken by stock market charts, which alter their scales daily depending on how far the market has moved in either direction. Are people misled? Probably not. We’ll see if the PCC agrees.