Why the popular ROI numbers don't survive contact with a CFO
Three kinds of numbers show up in most AI ROI presentations, and none of them hold up to a direct question about cash.
- Survey-based productivity claims. "73% of employees report feeling more productive with AI tools." This measures sentiment, not output. It has no denominator, no baseline, and no connection to a cost or revenue line.
- Best-case demo timing. A task that took an analyst forty minutes now takes the AI system four minutes, measured once, under conditions chosen to showcase the tool. Production performance, with real edge cases and real review overhead, is a different number.
- Vendor-supplied benchmark ROI. A number produced by the company selling you the tool, based on their customers' averages, not your workflow, your labor cost, or your error tolerance.
A CFO asking "what did this actually save us last quarter, in dollars" can't get an answer from any of these three. That question is coming eventually. The method below is built to answer it before it's asked.