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The Weird and Very Real World of Excel-Error Research

The Rogoff-Reinhart blunder is a prominent example of a very common problem


They're calling it the "Excel Error Heard Round the World": Kenneth Rogoff and Carmen Reinhart's widely cited paper about the relationship between public debt and economic growth was revealed Monday to have grossly misstated economic growth for high-debt countries, all because of a forehead-smackingly simple error in an Excel spreadsheet. ("It is sobering that such an error slipped into one of our papers despite our best efforts to be consistently careful," the paper's authors said on Wednesday.)

The debate over Rogoff and Reinhart's pro-austerity research turns on other issues than this single error, but the Excel error has inspired the most glee. There's something gratifying about Ivy League economists fouling up a rather simple spreadsheet. What's less funny are the odds that your bank, your government, or you have fouled up an important spreadsheet just as crucially (if not as influentially). 

"This type of stuff probably happens all the time. What's unusual here is that someone checked it," says Ray Panko, a professor at the University of Hawaii and the elder statesman of small coterie of research academics who study—yes—Excel errors. Panko's meta-analysis of several such studies, he claims, indicates that 84 percent of spreadsheets contain some kind of materially significant error. But fellow Excel guru Stephen Powell, at Dartmouth's Tuck School of Business, counters that it's hard to know what the exact figure is, but he agrees that Rogoff's recent error is not anomalous—Powell says he's examined "hundreds, if not thousands," of spreadsheets from companies with errors just as egregious.

There are ample anecdotes to support Panko and Powell's claims. In 2012, JP Morgan discovered that it had been grossly miscalculating a risk-management measure—possibly for years—due to a mischievous Excel formula. Last summer, Olympics ticketholders were baffled when the London 2012 Olympic Games committee oversold the synchronized swimming event by thousands of tickets--a hapless clerk had entered "20,000" instead of "10,000" in a spreadsheet cell.  A year prior, the town of Framingham, Massachusetts, announced that it would request $600,000 in state aid to cover a budget shortfall caused by miscalculating "monstrous spreadsheets." You can even find huge copy-paste errors in Fed Reserve spreadsheets if you comb through them.

Excel experts agree that the reason snafus like this, and like the Rogoff-Reinhart mishap, happen is that Excel is at once powerful enough to support enormously complex models, and easy enough for novices to use. 

So how do we keep the novices from derailing the world with bad spreadsheet formulae? Every summer, Excel enthusiasts from academia, finance, accounting, and other bean-counting professions gather in London at the annual conference of the (not-made-up) European Spreadsheet Risks Interest Group—or "EuSPRIG," to the hip. Results from a conference questionnaire "Why are we here?" on EuSPRIG's website gives a good glimpse into the culture of the Excel enthusiast world. One person wrote, "Because its fun! Also because the world needs us…," while another joked:

To solve life’s great question: 

B2 or not B2

=OR(B2, NOT(B2))

At EuSPRIG's conference, attendees hear talks like "Spreadsheet Hell," "Spreadsheets and the Financial Collapse," and "The Lookup Technique to Replace Nested-IF Formulas in Spreadsheet Programming."

Dire names, perhaps, but this event wouldn't exist if it weren't for the scourge of "uncontrolled and untested spreadsheet models." We could easily snicker at this earnest, incredibly dull world of spreadsheet-risk management, but the consequences of the Rogoff-Reinhart snafu are no laughing matter.

EuSPRIG gathers again this July, in London. Not a few of us ought to consider buying a plane ticket.