According to Professor Tom Grossman, author of the popular EuSpRIG paper “Spreadsheet Engineering: a Research Framework”, spreadsheet best practices are “Situation Dependent”, a view that is supported widely within the practitioner community. Guidance on spreadsheet best practice is therefore gradually emerging, as it depends upon what you are doing. In a recent paper, Tom Grossman and Ozgur Ozluk describe three Spreadsheet Engineering Methodologies. They find it credible that each of the methodologies enhances productivity, accuracy and maintainability for large financial planning models.
Here are some more documents to get you started on the subject of best practice.
How do you know your spreadsheet is right? More than fifty Principles, Techniques and Practice of Spreadsheet Style by Philip L. Bewig July 28, 2005. With references.
Spreadsheet Modelling Best Practice (1.4MB pdf) kindly donated by Louise Bartlett of IBM Business Consulting Services. Written by Nick Read and Jonathan Batson when Business Dynamics were part of PriceWaterhouseCoopers (PWC), published 1999 by the Institute of Chartered Accountants in England and Wales (ICAEW).
In a "Software Management" article (Jan 2001) "Software Defect Reduction Top 10 List" (121K PDF) Barry Boehm and Victor Basili predict "The ranks of 'sorcerers apprentice' user-programmers will also swell rapidly, giving many who have little training or expertise in how to avoid or detect high-risk defects tremendous power to create high-risk defects."
However, following Tom Grossman’s observation that best practice is situation dependant, David Colver questions with qualified examples that there may be no such thing as good practice. Acknowledging both points of view, Angus Dunn sets out a set of Required and Desirable spreadsheet practices, with a further set of practices to be Avoided.
Professor Ray Panko, University of Hawaii, gave some comprehensive guidance on testing spreadsheets at the EuSpRIG 2006 conference. Ray’s paper "Recommended Practices for Spreadsheet Testing" is available here.
Dr Louise Pryor gave a succinct outline of the principles of testing spreadsheets in her paper “When, Why and How to test spreadsheets”. In her follow up paper, she describes why merely establishing correctness of a spreadsheet may not be enough. Grenville Croll describes how a large accounting firm reviews spreadsheet models for accuracy. Harmen Ettema and colleagues from Price Waterhouse Coopers describes another approach – building a shadow model – to determine accuracy in important spreadsheet calculations. Simon Murphy describes his commercially based spreadsheet review process.
Dr John Raffensperger of the University of Canterbury, Christchurch, New Zealand, gave a memorable presentation at the EuSpRIG 2001 conference in Amsterdam on “New Guidelines for Spreadsheets”.
Bill Bekenn and Ray Hooper draw upon the Toyota automotive manufacturing methodology to describe a set of techniques “Poka Yoke” – Japanese for “Mistake Proofing” – to reduce the possibility of making mistakes in the first place.
Pat O’Beirne draws from the long history of database development to outline a methodology for making small but important improvements to spreadsheets without altering their fundamental design. Refactoring is a change made to the internal structure of software to make it easier to understand and cheaper to modify without changing its observable behaviour.
Ray Payette describes how to use some of Excel’s built in features to document spreadsheets, and gives copious examples in his paper “Documenting Spreadsheets”.
Dr Louise Pryor gives a brief characterisation of the purposes and forms of documentation in and of spreadsheets. Jocelyn Paine describes how to document spreadsheets with pseudo-code using an exercise with cash-flow and loans by way of example.
|A number of vendors including Clusterseven, EASA, Prodiance, Qtier Rapor, Resolver Systems, Ringtail XL, Risk Integrated, Spectrum Global and Xenomorph describe their various approaches to delivering safe and effective spreadsheet based systems.|
|Guidance from Microsoft|
|Microsoft have attended EuSpRIG on two occasions and have provided useful guidance on the development of better quality models. Firstly through a 2006 paper from Brandon Weber entitled “Strategies for Addressing Spreadsheet Compliance Challenges” and secondly in a 2008 paper directed at Accounting and Finance Professionals, Mbwana Alliy and Patty Brown focus on a number of key issues.|
|Spreadsheet Control Projects|
Andy McGeady and Joseph McGouran described a large project they had been involved with at Allied Irish Bank (AIB) to control the legions of spreadsheets in use within the Capital Markets division. They offer clear and prescient advice to others who would seek to embark upon such a project. Jamie Chambers and Mark Hamill describe a similar project at an unnamed European Investment Bank to control the use of end user computing tools for business critical applications.
Sebastian Dewhurst describes how he has used his company's technology to transform critical spreadsheets into Web based applications at Zurich Financial.
Thomas Lemon and Ewen Ferguson describe their service based approach. They have worked with a number of organisations, ranging in size up to huge multi-nationals, to help them build appropriate spreadsheet governance frameworks, including the design and implementation of policies, minimum design standards, control processes, training and awareness programmes and the consideration and implementation of spreadsheet management tools.
Ben Rittweger and Eoin Langan examine in the context of financial reporting, the controls that organisations have in place to manage spreadsheet risk and errors. Their recent findings support previous findings of Panko, that errors occur frequently in spreadsheets and that there is little or unenforced controls employed, however this research finds that attitudes are changing with regard to spreadsheet risk.
|Controlled Development using Spreadsheets|
|Spreadsheets can be safely used to build complex applications. The approach to this must be careful and controlled, incorporating the wide ranging aspects of a proper software development methodology. Susan Allen describes such a project that has gone live at Lloyds TSB bank in 2009.|
There is an emerging body of best practices for teaching spreadsheet use in scholars and students. Francoise Tort outlines some curriculum design principles. She suggests key principles for spreadsheet teaching and illustrates them with teaching guidelines.
Simon Thorne describes a new MSc module in End User Computing Risk Management. This pulls together much of the research and practitioner experience in Spreadsheet Risk Management to arm the next generation of finance spreadsheet champions with the relevant knowledge, techniques and critical perspective in an emerging discipline.
Almost ten years ago, David Chadwick, a EuSpRIG founder, and Rodney Sue outlined a teaching approach which had been devised to help students to reduce their likelihood of making common errors during spreadsheet development.
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