Derived Classification: Strength Levels

The ORS doesn’t ask “what strength level is this job?” It collects discrete data points, weight lifted, frequency of lifting, sitting duration, then derives strength classification through defined rules.

A job is classified as “light work” if it requires lifting or carrying 11-25 pounds occasionally. But if that same weight is lifted frequently, the job becomes “medium work.” Strength level emerges from the interaction of weight and duration.

This illustrates a broader pattern in classification design: high-level categories that seem natural (sedentary, light, medium, heavy, very heavy) are actually composites of multiple underlying dimensions. The classification logic is a design choice, not a discovery.

The ORS makes this logic transparent. The Handbook of Methods includes decision tables showing exactly how lifting weight, lifting frequency, and sitting/standing combine to produce strength classifications. This transparency allows users to understand, and potentially disagree with, the classification scheme.

Related: 02-molecule—faceted-classification, 06-atom—critical-job-function-vs-task