HCD.11:5.1 - Correct arithmetic, failed compatibility, later independent performance
Learner-L17 is a fictional person. The attempts below are constructed observations for learning how to assess; they are not observations of Engineer-E27, Engineer-P14 or programme participants.
The task is to recommend a defensible continuation for an engineering change service. HW3/FW8 is required. The supplied financial assumptions give approximate NPVs of 48.9, 51.6 and 44.6 thousand for alternatives A, B and C. B’s highest NPV does not supply compatibility: its available report concerns FW7. A needs a further shared-power check. C retains HW3/FW8 and uses SCHED2, with two hours of required checks per change and one hour of preparation per homogeneous batch of at most four.
With 24 test hours available, ten changes need 20 + 3 = 23 hours; twelve need 24 + 3 = 27. C can therefore support a proposal for ten, not twelve, with two new changes per week left in the queue. The release manager must agree to that limit and retains the release decision. These engineering criteria are stipulated case facts, not general engineering or safety guidance.
The assessed contribution is to inspect configuration evidence, preserve required checks, and explain a supported continuation and its queue consequence. L17 has the reports, task tables, calculator and ordinary AI assistance; no teacher hint is permitted during an independent attempt. The assessor observes source and assistant traces and asks for an explanation only where needed to attribute the conclusion. In the two fresh cases below, the trace places L17’s recognition before any teacher or AI cue names the mismatch; ordinary tool access remains available.
| Attempt and conditions | Constructed observation | Judgement and inference |
|---|---|---|
| First attempt, no teacher cue | L17 calculates the financial ordering correctly and recommends B without noticing that the report is for FW7. | Calculation is supported. The compatibility criterion fails; the first recommendation is unsupported. |
| Same task after “Which configuration was tested?” | L17 finds FW7, withdraws B and explains A’s remaining check and C’s bounded ten-change proposal. | The correction is supported with a configuration cue. Independent detection has not been shown in this attempt. |
| Fresh representative case, ordinary means, no cue | L17 personally finds a mismatching report and explains why the higher financial value cannot settle compatibility; L17 proposes the supported C limit and queue return. | Independent configuration checking and bounded continuation are supported in this case. |
| Second fresh representative case, ordinary means, no cue | L17 again detects the mismatch, traces the relevant evidence and explains the 23-hour limit and remaining queue. | The specified contribution is supported across the two fresh cases, with a small-sample boundary. |
The result does not average the four attempts. It preserves the original miss, the helped correction and the later independent observations. For local reversible practice planning in these tested conditions, the practitioner can preserve the supported calculation and configuration contribution and finish that decision. A proposed material resource change raises a separate question: select its observation when it is obtainable and worthwhile for the next use, rather than making it a condition of retaining the contribution already demonstrated. These observations do not establish performance across every engineering configuration or authorize a release.