5 October 2020

IT experts, including BCS members, have questioned why Public Health England used Excel for a scheme as large as NHS Test and Trace after a technical error led to nearly 16,000 cases going unreported.

Adam Leon Smith, Fellow of BCS, The Chartered Institute for IT, and Chair of BCS’s Special Interest Group in Software Testing commented: “It is very surprising to hear that an enterprise scale system, presumably developed by professional technologists, is expected to run on Excel. Many large organisations refer disparagingly to Excel-based applications as "end-user driven architectures" and spend lots of time trying to decommission them for reasons relating to security, control and stability. This is mostly because Excel is designed for end-users not complex systems, has well-known scalability limits, and will not handle unexpected situations in a way that interacting systems will be able to recognise. It sounds like these limitations have manifested in real problems in this case, and this is exactly why databases are normally used in enterprise applications.”

He continued: “Even if presented with a system that did rely on Excel, one of the first things that should have been identified through a testing process was a limit to the data volume it could process. This is known as "scalability testing" and should start with identifying the required criteria (should handle millions of cases), identify the amount of test data required to verify the system, and confirm that no defects exist.”

“After seeing technical website errors a few weeks ago leading to a lack of test availability, followed by these new failures, the BCS Special Interest Group in Software Testing would be happy to assist the relevant government departments in developing a better testing strategy for their contact tracing toolset.”

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