ORIGINAL COMPANY-CONTEXT PRACTICE
Aggregate gas-quality readings using compatible weights
Original practice scenario: A hypothetical energy report combines gas streams with different measured volumes and energy-content readings. Explain why a simple average can misstate the combined result.
Written for independent practice using company context; this is not a verified question from a company interview.
A REASONED APPROACH
Model answer.
Choose a consistent physical basis and weight each valid measurement by the associated flow over its supported interval. An unweighted mean gives a tiny stream the same influence as a large one.
Work through it
- Retain stream identity, measurement interval, flow unit, reference conditions and quality status, aligning intervals before combining observations.
- Convert compatible measures under an approved rule and compute weighted contributions from valid overlapping coverage, preserving unavailable readings as missing evidence.
- Report total supported flow and the combined measure with coverage, reconciling contributions to the original streams and separating intervals with insufficient quality data.
Tradeoffs to discuss
- Time alignment improves interpretability but may require resampling assumptions; coarse aggregation uses fewer assumptions while hiding short-lived variation.
Common pitfalls
- Do not mix volumes measured at incompatible reference conditions without an explicit conversion.
- A missing quality reading cannot safely contribute a zero value to a weighted average.