Aspiring bank robbers, take heed. New statistical analyses of confidential bank data suggest that mountains of riches aren't in your future, but that a jail cell is.
"The return on an average bank robbery is, frankly, rubbish," wrote the authors of a new article about the economics of British bank robberies in Significance, a quarterly statistics journal published by the American Statistical Association and Royal Statistical Society. "[I]t is so low that it is not worth the banks' while to spend as little as £4,500 [$7,000] per cashier at every branch on rising screens to deter [bank robberies]."
These and other conclusions emerge from a confidential data set obtained by economists Neil Rickman and Robert Witt at the University of Surrey, and Barry Reilly at the University of Sussex. The trio spent months negotiating with the British Banker's Association, or BBA, to obtain confidential records detailing 364 bank heists that occurred over three years in the U.K.
The data reveal how many robbers pulled off with each heist, if they were armed, what security measures were present, how much they escaped with, whether or not they were caught, bank location (and thus proximity to police stations), and more. Such detailed bank robbery data is not available in the U.S. where, by contrast, if U.S. banks even record most of these details, they are lost in anonymity in the FBI 's quarterly reports on bank robberies.
"There hasn't been a lot of work done on this problem because most data sets only tell you if a robbery occurred. The size of a robber's takings is sensitive to banks, so they keep it confidential," Rickman says. "We're very lucky to get the data we have."
Game of numbers
About 80,000 robberies occur in the U.K. each year, and of these less than 0.5 percent were bank robberies. Averaged across 10,500 bank branches in the region, the odds of a bank robbery at any particular branch in recent years work out to about one in 100. "One element to being a successful bank robber is not only walking away uncaptured, but the amount of money you walk away with," Rickman says. "Walking away with £10 [$15], for example, isn't something I'd consider successful."
By averaging the work of the best criminals with the worst—and every crook in between—from 2005 through 2008, the data paint a bleak picture for criminals eyeing a future career in larceny.
The data reveal that the average U.K. bank robbery consists of 1.6 robbers and nets £20,330.50 ($31,600) per heist, with a standard deviation of £53,510.20 ($83,000). Assuming an equal share, the average take was £12,706.60 ($19,700) per robber, per heist—roughly equivalent to a coffee shop barista's annual salary.
Wielding a gun increased the average haul by £10,300.50 ($16,000), as did adding more robbers to a raid. But going alone netted the average robber more money, because the amount gained by increasing a heist party did not outpace the hit taken by splitting an individual robber's spoils.
Dangerous career choice
The amounts are not chump change, Rickman noted, but bank robbing is risky business. Roughly 33 percent of U.K. bank heists end with no robber earning anything, and about 20 percent of raids end in capture. The odds of arrest get worse as a robber attempts more heists. On a robber's fourth heist, for example, the odds of capture compound to 59 percent. "Somehow, I expected most bank robbers to be doing much better than what the data actually show," Rickman says. "Would I pick up a firearm to share 20,000 quid with another person? Probably not."