OPS.15:4.2 - Define the claims and measures
For each decision-bearing quantity, make its meaning recoverable. A ratio needs its numerator, denominator and eligibility rule. A duration needs its start, end, unit and treatment of unfinished cases. A count needs its event or result identity, observation window and duplication rule.
Choose the interpretation with the receiving use. Completed-only cycle time may describe completed work; it cannot by itself describe how all admitted work is progressing. A due-date cohort contains work whose required completion date falls within the selected period. Open work whose deadline has passed differs from open work whose deadline lies in the future.
Use the following questions only where their answers affect the claim:
| Question | Consequence for the account |
|---|---|
| What belongs to the population? | Inclusion, exclusion, cancellations, diverted work and service classes change the denominator or reach. |
| When is the event observed? | Clock origin, cutoff, timezone where material, and reporting delay change the time claim. |
| What constitutes completion or acceptance? | Attempts, completed work, accepted service and a later release can be counted differently. |
| How is the value obtained? | Source, measurement rule, sampling and missing data determine what the number supports. |
| Can the values be compared? | Changed definitions, methods, mix or conditions may require recalculation on a common basis. |
Keep uncertainty explicit when it can change the decision. Use an interval, separate unknown category or qualified estimate appropriate to the claim. A precise display does not remove missing observations.