Every Copilot business case eventually produces the same slide: "users report saving X hours per week," multiplied by headcount, multiplied by a loaded hourly rate, equaling a number large enough to justify anything. The CFO nods, the renewal goes through, and nobody in the room believes the number — including the person presenting it.
You can do better, and you should, because the honest math for Copilot is frequently good. It just isn't the survey math. The survey math is so inflated that when reality eventually intrudes — usually via a usage report at renewal — it takes the credible gains down with it.
Why "hours saved" surveys overcount
Four mechanisms, all of them well-understood and all of them ignored:
- Estimation inflation. "How much time does Copilot save you weekly?" invites people to recall their best moment and project it across the week. The vivid memory of one 45-minute save becomes "a few hours a week" on the form. Self-reported time data diverges from observed time data reliably and always in the flattering direction.
- Saved minutes aren't harvested minutes. A meeting recap that saves 12 minutes does not produce 12 minutes of additional output. It produces a slightly earlier coffee. Fragmented micro-savings only convert to business value when they aggregate into something redeployable — or when they shorten a cycle time someone is waiting on. Multiplying minute-fragments by hourly rates is fiction arithmetic.
- Survivorship. Surveys get answered by people who use the product. The 40% of licenses sitting dormant don't fill in your form, but they absolutely show up on your invoice. The survey measures your fans; the cost measures your tenant.
- The demo-week effect. Sentiment surveys run in the honeymoon period capture novelty enthusiasm. The number you need is from month four.
Keep running sentiment surveys — they're useful as adoption health data and they catch friction early. Just stop calling the output ROI.
A survey tells you whether people like Copilot. A stopwatch tells you whether it's working. These are different instruments measuring different things, and only one of them belongs in a business case.