Joost Visser

Essential reading

Solver Max provides a collection of optimization model examples in Excel (using the Solver and OpenSolver add-ins) and Python.
Spreadsheet audit and review procedures are an essential part of almost all City of London financial transactions.
Creating a slow spreadsheet is easy. Creating an efficient spreadsheet requires more thought and application of specific techniques.
The twenty principles for good spreadsheet practice aims to reduce the amount of time wasted and the number of errors.
"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.
Every study that has looked for errors has found them in considerable numbers. Spreadsheeting's childhood is over.
95% of all spreadsheets contain errors. So, it is almost certain that your spreadsheets are wrong.
Good spreadsheets are essential for informing decision making. But most spreadsheets are not good. We help you make better spreadsheets.