HCD.24:5.1 - A correct ratio and an unsupported cause

This constructed exercise uses HCD.22’s personal diagnostic case. Pressure is already measured at 400 ± 4 kPa; flow is 99.5 ± 1 m³/h and power 22.3 ± 0.2 kW, compared with the supplied baseline of 100 m³/h, 400 kPa and 20 kW. The task’s qualified account states what the constant-efficiency resistance explanation would predict. No further worthwhile observation is obtainable within the case.

Work A correctly computes the approximate increase in the power-to-flow indicator, then recommends correcting increased resistance. Work B preserves the indicator change but says the unchanged pressure fails to support that simple explanation under its assumptions. The review criterion is whether the recommendation is warranted by the supplied evidence, rather than which work sounds more decisive.

The reviewer first prefers A because it offers an action. Comparing the observation-to-recommendation parts reveals the missing inferential step. Calibration asks the reviewer to identify the expected pressure under A’s account and compare it with the measured pressure. The reviewer then returns a specific comment: retain the arithmetic, withdraw the resistance-specific remedy and state the remaining explanation question and present limit.

The author accepts the mismatch but initially adds “take another pressure reading.” The reviewer points to the already obtained reading and exhausted useful-observation condition. The author replaces that instruction with a bounded conclusion and a return for a qualified alternative explanation if the receiving work requires one. A prepared mentor resolves any dispute about the subject model; peers do not authorize a real plant intervention.

Both sides now have a learning result to inspect. The author revised the inference; the reviewer corrected a preference for actionable-sounding text and applied the criterion. The initial and helped judgements remain distinct. The contrasting case in §5.3 supplies a supported action recommendation. These exchanges require their own preparation, time and qualified help in HCD.28’s product cost.