An Average Delivery Time Is Not a Promise

For the fictional sample, lead time means elapsed calendar days from the recorded accepted order to confirmed usable completion at the destination. A placement request, dispatch event, first partial arrival and full completion are separate milestones. We supply each endpoint rather than determining acceptance or product suitability.

A duration measured from dispatch can be shorter than one measured from accepted order for the same event. Mixing the two produces an inconsistent sample. Similarly, working days, calendar days, time zones and partial-day rounding can change a calculation. Write the chosen convention before subtracting dates.

The main six completed durations are four, five, six, seven, nine and eleven days. They belong to the same stipulated item and route class, using the same definitions. Actual shipments may not be comparable even when they share a supplier name. We exclude changes in specifications, transport routes and service arrangements from the first exercise.

A separate partial-delivery illustration has first arrival at elapsed day five and full usable completion at nine. Its duration under our definition is nine, not five. That does not mean the first arrival has no value; it answers a different milestone question. Keep the event's original dates and status visible. This guide does not prescribe handling or inspection, interpret a real contract or authorize changing promised dates. The useful starting output is a reproducible duration definition and a bounded group of comparable completed observations.