Trust the data: when does the advice fit?

A dispatch sheet lists 18 parcels. You count 17 on the trolley before it leaves. A direct count can catch this specific mismatch. Recount the trolley and check the sheet. Change one condition: One line is a replacement label for a parcel already counted. The count is still useful, but the unit changed. Reconcile unique parcels rather than adding labels.

Closed support requests doubled after staff were told to close every request before lunch. Repeat complaints are not tracked. Closures alone cannot show that customers received a useful resolution. The reporting rule leaves an important outcome unobserved. Change one condition: The report now links closures to confirmed resolution and repeat contacts. The broader check is more informative. Inspect how it was collected and what it still misses.

Three visitors prefer the new exhibit. Two prefer the old one. You must decide whether to rebuild it. These are five real preferences, not a stable estimate for every visitor. The cost and reversibility of the rebuild matter. Change one condition: The same five people tried only one version each, on different days. The comparison mixes people and conditions. The apparent advantage cannot be attributed to the exhibit alone.