hardScenarioDesignMidSeniorStaff
One machine's clock is ninety seconds ahead of the rest of the plant. Which of your numbers are wrong, and how would you have found out?
7 min readUpdated 2026-08-15
Answer
Short answer
Every derived figure that joins on time is affected, and none of them error. Duration and attribution metrics take the skew directly, so a shift with twelve stops mis-measures availability by nearly four points, and only storing both event time and ingestion time makes the offset visible.
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Likely follow-ups
- The offset chart shows a sawtooth rather than a straight line. What is happening?
- How do you compute a correct stop duration when start and end come from two systems?
- Would you correct the stored history or correct at query time? Defend it.
- A clock steps backwards by two minutes. What does that do to your primary key?
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