HCD.19:5.1 - A correct reader exposes a defective handout
The time-use case in HCD.18 provides the tasks and subject criteria. In a preserved clean-context agent walkthrough, the reader first saw M0: the handout defined task time from first touch to handoff and gave one uninterrupted example. The reader knew arithmetic and time-accounting distinctions; novice behaviour was not simulated.
For one person’s interrupted report, the first response was:
| Requested quantity | First answer |
|---|---|
| Active report work, 09:00–09:30 and 11:30–12:00 | 60 minutes |
| Incident work, 09:30–11:30 | 120 minutes |
| Report elapsed turnaround, 09:00–12:00 | 180 minutes |
| Total active work across both tasks | 180 person-minutes |
| Incident share | 120/180, or two-thirds |
The reader explained that it brought the active/elapsed distinction and person-time meaning from prior knowledge. M0 supplied the intervals and start-to-handoff wording; its uninterrupted example could not distinguish the two quantities.
The supported diagnosis is a material defect despite reader success. The central instruction assigns elapsed turnaround to a question about consumed effort. The subject criterion identifies the defect directly; the observed response shows expert correction of it. Neither observation establishes how a less-prepared human would perform.
The repair M1 states that active effort sums the intervals in which the named person works on the task, while elapsed turnaround spans first start to handoff. It separates person, task, active intervals, person-time, first start, and handoff in the record; works the interrupted case; and distinguishes a population’s person-time from wall-clock duration. This is a connected explanation–representation–example repair, not a cosmetic change to the word “time.”