Wright's own '80% curve' is defined over a whole production lot's average cost, not an individual unit's cost — a distinction the modern restatements drop

economicswrights-lawlearning-curvetp-wright-1936cost-curvesspecification-gap

Wright's own text defines his headline percentage precisely: the eighty percent curve "represents the factor by which the average labor cost in any quantity" is multiplied to determine the average labor cost for a quantity twice as large. This is a claim about the cumulative average cost of an entire production lot doubling in size — not about the cost of the next individual unit built.

Neither restatement checked against the primary carries that distinction. New Things Under the Sun describes "a consistent decline in per-unit production costs," and Our World in Data's worked example tracks "the price of solar panels" at successive points of cumulative capacity — both unit- or price-framed, neither specifying the whole-lot-average construction Wright's own text uses. This is a genuine specification gap, not a flat contradiction: a cumulative-average-cost curve and a unit-cost curve converge as quantities grow large, so the two framings agree in the long run even though they answer different questions about the next unit off the line. A reader taking either modern restatement at face value would not know which of the two models "Wright's Law" technically names in the 1936 original.

This sharpens rather than undermines claim-wright-1936-defines-cost-as-power-law-of-cumulative-quantity and the general statement in claim-wrights-law-cost-falls-per-cumulative-production-doubling: the log-log-straight-line mechanism matches, but the quantity on the cost axis is more specific than either popular summary states.