Wright’s Learning Curve, explained.
Wright-style learning curves describe a power-law relationship between cumulative production and cost under a specified cost convention.
Why it happens
The board uses a unit-cost index of one thousand at cumulative output one. Each doubling multiplies unit cost by progress ratio b; the exponent is log₂ b.
Wright-style learning curves describe a power-law relationship between cumulative production and cost under a specified cost convention.
Read the result
The horizontal progress variable counts doublings of cumulative output. It is neither calendar time nor the count of individual additional units.
A worked example
Apply a progress ratio twice
Keep the progress ratio at eighty percent with initial unit-cost index one thousand.
Double cumulative output once to obtain unit cost eight hundred.
Double again to output four and unit cost six hundred forty, distinguishing a second proportional reduction from a fixed subtraction.
OPTIONAL DEEPER DETAILGo deeper: inside the model
Inside this model
The board uses a unit-cost index of one thousand at cumulative output one. Each doubling multiplies unit cost by progress ratio b; the exponent is log₂ b.
Where this idea is useful
A practical use
Distinguish a cost reduction per doubling of cumulative output from a reduction per year.
A common misconception
“An eighty-percent progress ratio means costs fall eighty percent each year.”
It means cost becomes eighty percent of its previous value per cumulative-output doubling under this convention, with no year assigned.
What this explanation leaves out
- A fixed unit-cost convention and stable ratio are supplied. Cumulative-average accounting differs, and the curve is not evidence that any technology must follow this forecast.
Is the unit-cost convention interchangeable with cumulative-average cost?
No. Historical learning-curve accounting can use different conventions; the board explicitly models unit cost at cumulative production levels.
Which cumulative-output assumption turns an observed relationship into a future projection?
Associated thinkers
Associations marked provisional are awaiting source review.
Further reading
Explore the original research or the teaching reference behind this experiment.