Funnel Forensics begins with a rude act: print the funnel and write the user-facing job beside each step. If you cannot, the step is a log line. Log lines are allowed in engineering. They are unkind in a board pack.
The classic public lie is a conversion path that includes “viewed pricing” as if viewing were intent. Another is a duplicated checkout_started from a web pixel and a mobile SDK sharing a name after a white-label. The chart shows a mysterious swelling. Someone suggests a growth experiment. The swelling was a merge.
Silent errors
After a release, an event can stop firing while the product still works. The funnel then “improves” because the denominator died. Always pair a conversion claim with a volume check on the first step against an independent count — store downloads, billing receipts, even a crude server log.
If those two disagree, you do not have a product story yet. You have a ticket. Shipping the ticket is less glamorous than a new onboarding illustration. It is usually the work.
What we will not claim
We will not tell you a funnel “proves” a design is wrong. Design may be wrong. So may the spine. Funnel Forensics is the habit of asking which, out loud, before the illustration budget moves.