Impact of errors in operational spreadsheets

All users of spreadsheets struggle with the problem of errors. Errors are thought to be prevalent in spreadsheets, and in some instances they have cost organizations millions of dollars. In a previous study of 50 operational spreadsheets we found errors in 0.8% to 1.8% of all formula cells, depending on how errors are defined. In the current study we estimate the quantitative impacts of errors in 25 operational spreadsheets from five different organizations. Within these 25 spreadsheets we identified 381 potential errors, of which 117 (31%) were confirmed as errors by the developers of the spreadsheet. Among these confirmed errors, 47 (40%) had no quantitative impact on the results. Among the remaining 70 confirmed errors, the largest error was $100 million; however, 9 of the 25 spreadsheets tested had no errors at all.