DIAG-3 · Diagnosis · Heuristic: strong prior, re-verify periodically
Twyman's law
Melvin SalasVerified 24 September 2026
The law
The more surprising a reported KPI movement, the more likely it is a measurement or pipeline artifact than a real market event.
Scope
Normal operating regimes; the prior inverts in genuinely volatile windows (crisis periods, accounts at the noise floor).
What this licenses you to do
Fixed triage order for any surprising delta: (1) measurement and definition audit, (2) mechanical decomposition, (3) market hypothesis last, and require confirmation from an independently instrumented source. In Google Ads, one measurement check is timing: the primary conversion columns report a conversion against the date of the click, not the date the conversion happened, so a conversion that happens days after its click is added to that earlier day and recent days can still rise.
Evidence
Ehrenberg (1975); Kohavi, Tang & Xu (2020) catalogued extreme-result bugs.
Riibon's own analysis is held to these laws
The laws on this site are a public subset of the rulebook Riibon's analysis works to. Before a metric movement is called a market event, the order of checks they set has to rule out the measurement first.
Ask the Riibon app why a number in your account moved, and see which checks it ran first. Access starts with a short call: we look at your ads together, then run them for you or set the app up with you.