An obvious risk is that a spreadsheet might contain a computational error that gives a misleading result. More subtely the outputs may be ambiguous or a model may contain hidden or unrealistic assumptions.
Spreadsheets use is widespreadand often in high profile and mission critical applications. Even where Organisations have made extensive use or proprietary databases there is often a need to supplement these with Excel spreadsheets, for instance one off calculations and to gather data from external parties not on Corporate networks. There have been a number of high profile spreadsheets in recent years:
An £8.6m reduction in profits for support services firm Mouchels was attributed to a spreadheet error
A US think tank under reports academic status of Virginians due to a cut and paste error
A key academic paper making the case for Austerity policies was undermined when is was discovered two Harvard Economists had made basic spreadsheet mistakes
Creating a spreadsheet solution is akin to software development – particularly when complex. A complex spreadsheet should therefore be managed like a mini software project with requirements definition, design, testing and documentation.
The examples above were taken from the European Spreadsheets Risk Interest Group www.eusprig.org.