Microsoft Excel – and other spreadsheet programmes – allows the creation of models of infinite complexity. The main advantage of Excel - an easy-to-use, almost intuitive, “programming” interface – is potentially its main disadvantage. Spreadsheets get started quickly and may or may not be properly maintained. Complex calculations can be resolved in a cell-by-cell iterative manner, making error location difficult. Solutions tend to be extended over time – often by different people – which compounds the problem. A myriad of pre-packaged functions is available, but the choice of the appropriate – or inappropriate – function is entirely at the developer’s discretion.
If you - or someone in your team - is working with Excel, then please pay attention to:
• Specification – define what you’re trying to do, record sources of information
• Security – avoid breaking a working version, making sure everyone is using the correct version, the use of passwords and their limitation
• Style – managing constants, units of measurement etc for consistency, handling unwieldy formulae.
Patrick O'Beirne's Spreadsheet Check and Control provides a nice "How To" guide. [Review]
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