Comparisons should use equipment operating under reasonably similar conditions and account for the number of installed units, equipment age, occupancy, and maintenance practices.

Useful measures may include failures per installed unit, repair cost per unit, work orders per unit, downtime, warranty claims, energy performance where measurable, and average useful life.

Hotels should avoid drawing conclusions from a small number of isolated failures. Larger datasets collected over meaningful operating periods provide stronger evidence for future product decisions.