Assumptions and method
Uses Wright’s cumulative-average convention, not effort on the nth unit. It assumes continuing learning without disruption or a plateau.
Test a scenario
Use the result in a decision
Keep effort, elapsed duration and skills distinct.
Uses Wright’s cumulative-average convention, not effort on the nth unit. It assumes continuing learning without disruption or a plateau.
Set a baseline and change one assumption to compare outcomes.
A worked example
Follow the fixed teaching example
- The exponent is log₂(0.8). Eight units represents three doublings.
- Cumulative average = 100 × 0.8³ = 51.2 hours per unit; cumulative total = 8 × 51.2 = 409.6 hours.
These illustrative inputs describe a project scenario, not a published benchmark. All monetary inputs use the same currency and price basis.
- First-unit effort (hours)
- 100
- Progress ratio after each doubling (%)
- 80
- Cumulative units
- 8
- Cumulative average effort per unit
- 51.2 hours
- Cumulative total effort
- 409.6 hours
Interpret the output only within the assumptions above. Changing the inputs changes the result; it does not validate the inputs.
Source & credit
Theodore P. Wright is associated with the cumulative-average learning curve. It differs from a unit-time curve.
NASA: learning and cost-improvement curves
T. P. Wright (1936): Factors Affecting the Cost of Airplanes
This is independently written code and explanation of the underlying method. The linked publication, its diagrams and its trademarks remain its owner’s material; no permission to reuse them is implied.