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• Studies by Professor Ray Panko [Spreadsheet Research Site]: on average, 30% of spreadsheets contain errors, including wrong data and wrong formulae.

  Estimates that people make around one error every hundred cells.

• Research by Coopers and Lybrand: in spreadsheets with over 150 rows, over 90% contained at least one significant mistake in a formula.

• Study by the Customs and Excise Computer Audit Unit: only 11% contained errors, but those that did were out by amounts varying from £100s to £1Ms.

• A Fortune 500 firm used discounted cash flows in a spreadsheet for evaluating investment proposals. The discount rate and discounting formula had been set up many years ago by an employee who had since left. They were not documented. Although the prime rate rose from 8% to over 20% between 1973 and 1981, the spreadsheet was kept at 8%. [A. Dhebar, Managing the Quality of Quantitative Analysis, from Sloan Management Review, vol 34 (2), pp. 69-75, Winter 1993.]

Some of these findings are cited by New Scientist [``Fatal Addition'', 16th August 1997].

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