Professor Barry Reilly

Robbing banks is - statistically speaking - a bad idea, according to a new report co-authored by a Sussex economist.

Crime is an economic activity like any other, say Professor Barry Reilly and his two academic colleagues at the University of Surrey.

So they considered the risks and rewards of the average bank job by analysing data from the British Bankers’ Association. And the data gives a picture of the profitability of bank robberies that is rather different from the popular imagination or from the depictions in big-budget movies.

The average proceeds from a bank robbery were £20,331, although one-third of robberies yielded nothing at all. The average takings per person per successful raid were a modest £12,707, equivalent to less than six months of the UK average wage.

If a robber carries out multiple raids to boost this income, probability says that after four raids he will be in prison for some time and therefore unable to earn at all.

There was a clear connection between the number of raiders and total takings: the bigger the gang, the greater the success, with every extra gang member raising the average take by £9,033. However, with extra individuals to share the proceeds, the haul per person decreased.

The other major factor was whether the robbers were armed: the threat of using a gun increased the average haul by £10,300.

Fast-rising metal security screens reduced the probability of a successful raid by one-third. Even so, the financial losses to banks through raids are reasonably low compared to the cost of installing screens, which might explain why only 12% of UK branches have them.

The three economists acknowledge that bank robberies involve other costs (such as social and psychological ones). They also note that additional data would allow valuable follow-up research.

But their conclusion is quite clear: “As a profitable occupation, bank robbery leaves a lot to be desired,” they say. “The return on an average bank robbery is, frankly, rubbish.”

The report is published today (12 June) in Significance, the magazine of the Royal Statistical Society and the American Statistical Association.