Ben Goldacre
The Guardian,
Saturday January 19 2008
In 1954 a man called Darrell Huff published a book called “How to lie with statistics“. Chapter one is called “the sample with built in bias” and it reads exactly like this column, which I’m about to write, on a Daily Telegraph story in 2008.
Huff sets up his headline: “The average Yaleman, Class of 1924, makes $25,111 a year!” said Time magazine, half a century ago. That figure sounded pretty high: Huff chases it, and points out the flaws. How did they find all these people they asked? Who did they miss? Losers tend to drop off the alma mater radar, whereas successful people are in Who’s Who and the College Record. Did this introduce “selection bias” into the sample? And how did they pose the question? Can that really be salary rather than investment income? Can you trust people when they self-declare their income? Is the figure spuriously precise? And so on. Read the rest of this entry »