  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. We find that many errors have no quantitative impact on the
spreadsheet. Those that have an impact often affect unimportant portions of the
spreadsheet. The remaining errors do sometimes have substantial impacts on key
aspects of the spreadsheet. This paper provides the first fully-documented
evidence on the quantitative impact of errors in operational spreadsheets.
