Errors in Operational Spreadsheets

Abstract

Spreadsheets are used in almost all businesses, for applications ranging from the mundane to the mission-critical. Errors in the data, formulas, or manipulation of spreadsheets could be costly, even devastating. The received wisdom is that about 5% of all formulas in spreadsheets contain errors, and this rate is consistent across spreadsheets. However, this estimate is based on five studies, some of which are quite informal, and a total of only 43 spreadsheets. Our research was designed to deepen our understanding of spreadsheet errors. Specifically, we address three questions about errors in operational spreadsheets: what is the average cell error rate, how does it differ among spreadsheets, and what types of errors are most prevalent? We created a spreadsheet auditing protocol and applied it to 50 diverse operational spreadsheets. We found errors in 0.9% to 1.8% of all formula cells, depending on how errors are defined. We also found that the error rate differed widely from spreadsheet to spreadsheet.