Spreadsheets – Reliable Tool or Risky Relic?
When you hear about 16,000 Covid‑positive cases disappearing from the UK Test & Trace spreadsheets, courtesy of an XLS file limit, the question isn’t just “how?” but “why are we still trusting spreadsheets for serious forecasting?
‘To err is human but to really foul things up requires a computer’ is attributed to Paul Ehrlich, the American scientist: Public Health England proved it to be true of Excel when details of 16,000 Covid-positive cases disappeared from its Test and Trace spreadsheets in early October last year, resulting in 1,500 unnecessary deaths. Somewhere during an automated process, cases had vanished off the bottom of the spreadsheet, and nobody had noticed.
🧑💻 Why Excel Still Dominates …and Where It Falls Short
PHE contacted Tim Harford, the English economist, broadcaster and journalist about it and he wrote it up in the Weekend FT of June 24. When he asked Bill Gates about the problem, in the course of an interview for BBC’s How to vaccinate the world, Microsoft's founder said: “I guess… they overran the 64,000 limit, which is not there in the new format, so… It’s good to have people double-check things, and I’m sorry that happened.”
"It’s fine to celebrate success, but it is important to heed the lesson of failure.”
We all have Excel on our computers—it’s part of Microsoft's Office suite and we’ve been using the spreadsheets for years even if they are a bit fiddly and not always accurate. In fact, Excelinexcel’s website lists How to Fix the eight most common errors and gives no less than 15 hot tips. Early laptop converts will remember you needed a whole new language to drive Microsoft programs back then and Excel seems to be continuing this.
🧮Excel Dictates
Matt Parker, the author of Humble Pi, a book about mathematical mishaps and their consequences, notes that Excel’s own functionality combined with the mistaken assumptions of users will often introduce mistakes.
“As humans,” Parker notes, “we are not good at judging the size of large numbers.” A million seconds, he points out, is less than two weeks, but a billion seconds is 31 years. And even the mathematics of professionals can fail in critical situations, if our models of how things behave are incomplete.
“Type an international phone number into Excel, for example, and the program strips off the leading zeroes, which are redundant in a mathematical integer but not in a phone number. If instead you type in a 20 digit serial number, Excel will decide those 20 digits are a huge quantity and round them off, turning the last few digits into zeroes.”
🛠️Ho Hum
Harford reassures readers that trained accountants don’t make these sorts of mistakes. Felienne Hermans of Delft and Emerson Murphy-Hill of North Carolina State universities looked at over 15,000 spreadsheets and emails relating to Enron’s financial meltdown and found an astonishing number of spreadsheet errors. Their analysis shows:
🔹24% of Enron spreadsheets had at least one formula with an Excel error
🔹There was little diversity in the functions used in spreadsheets – 76% used the same15 functions
🔹Spreadsheets were significantly poor at long calculation chains.
Moreover, 10% of Enron’s emails either refer or send spreadsheets and they frequently discuss errors and updates.
📉 The Risks You Can’t Ignore
When spreadsheets become the backbone of forecasting:
🔹Version control becomes chaotic.
🔹Hidden formulas and manual links make audit‑trail weak. Sage+1
🔹Static models struggle to keep up with dynamic business drivers. blog.hurree.co
🛠️ Modern Forecasting With Purpose
Enter a system designed for financial agility:
✅ Customisable modules for departments, assumptions, memos, KPIs, and reporting.
✅ Multi-year planning (up to 15 years) including cashflow, P&L, balance sheet, and funds flow.
✅ “What-if” scenario modelling to test enrolment, staffing, capital projects, and more.
✅ Seamless integration with Sage, Xero, MYOB, SAP, and other accounting systems.
✅ Rolling forecasts and variance analysis to track actuals against budgets in real time.
✅ User-level permissions and collaboration tools for secure, multi-user access.
The takeaway? If you’re still using spreadsheets for complex or critical financial planning, you’re risking error, time‑waste and strategic mis‑alignment.
💡 From Risk to Confidence
In today’s fast‑moving business environment, relying solely on spreadsheets for budgeting and forecasting is not just old‑school—it’s dangerous. Your finance team deserves clarity, certainty and agility. By embracing a modern forecasting platform designed for transparency, accuracy and scenario planning, you transition from reactive firefighting to proactive strategy‑making. Don’t let hidden formula errors or outdated models undermine your decisions. Choose the tool built for the future—so your forecasts become your advantage, not your liability.
