Andrew D. Gordon

Essential reading

Research concludes unanimously that spreadsheet errors are both common and non-trivial. We must seek ways to reduce spreadsheet errors.
95% of all spreadsheets contain errors. So, it is almost certain that your spreadsheets are wrong.
Our spreadsheet methodology has criteria for designing, building, and validating spreadsheets to ensure that they work correctly.
See our bibliography of spreadsheet best practice, risk management, errors and testing, and methods for improving spreadsheets.
Spreadsheet errors are reduced by using good design. Our students do three assignments to acquire good spreadsheet design skills.
Spreadsheets have errors like dogs have fleas. Nine out of every ten spreadsheets suffer some error, and consequences can be severe.
"Oh My God" my formulas are not working! This article covers most of the reasons for Excel formulas not working. And how to fix them.
The twenty principles for good spreadsheet practice aims to reduce the amount of time wasted and the number of errors.