Statistics - Do they just make them up? Part Two

Searching for material for my teaching I came across a BBC Radio Four programme A Baby ASBO first broadcast in 2009. About five minutes into the programme a new initiative aimed at Primary School Children called Growing Against Gangs is introduced. The programme ran by an organisation called Gang Resistance Education and Training and is adapted from a similar scheme in the United States. The programme involves police officers delivering lessons to primary school children. In this programme we hear PC Emma Hart "teaching" some young children. She tells the children she is "going to through some facts" with them. She checks that they understand what facts are before telling them:

Most gang members make very little money ... 95% of drug dealers are working for less than the minimum wage you could earn at McDonalds ...

What PC Hart fails to tell the children that her "fact" is based on a paper published in the Quarterly Journal of Economics in 2000 by Steven Levitt and Sudhir Venkatesh An Economic Analysis of a Drug Selling Gang's Finances. The paper is based on data collected by Venkatesh on a Chicago gang in the mid 1980s whose activities included dealing crack.  In fact the paper although showing that the rewards for drug dealing were very much concentrated at the higher levels had concluded that average rewards were better than the participants would have gained in legitimate occupations. However these rewards were not sufficiently high as to justify the risks involved in gang activity. The activity could be better explained they argued by gang members hopes of high future earnings (when and if they made it higher up the drug dealing ladder) rather than current earnings.

This research has featured in Levitt's best selling Freakonomics and Venkatesh's Gangleader for a Day and have become generalised both in terms of all drug dealers and all places.  Although I am not a great fan of either book at least reading them meant I could spot the dodgy source being used by PC Hart as having established that the children knew what a fact was then provided them with at best spin, at worse a lie.  The sad news is I only heard it on the radio and was not present to point out to the kids the dangers of trusting what a police officer tells them.  A valuable lesson in Lambeth!