In lean six-sigma terms, what does first-pass yield measure in a UPS sort operation?

• A. The total number of shipments processed per hour.
• B. The proportion of units that pass a process step without rework.
• C. The average time to complete a sort.
• D. The error rate across all steps.

Answer: (B)

First-pass yield measures quality at the first attempt, by looking at the proportion of units that pass a process step without needing any rework. In a UPS sort operation, it reflects the share of shipments that are sorted correctly on the first pass without having to be reprocessed, relabeled, or re-sorted. The typical calculation is the number of shipments that go through correctly on the first try divided by the total shipments entering the sort. For example, if 950 of 1,000 shipments are sorted correctly on the first pass, FPY is 95%. This metric highlights process reliability and identifies opportunities to reduce rework, which saves time and lowers cost. Other options describe throughput (how many shipments per hour) or cycle time or overall error rate, which measure different aspects of performance and aren’t FPY.