Stated valuation barely responds to order-of-magnitude changes in the quantity at stake.
Desvousges's study found willingness to pay to save 2,000, 20,000 and 200,000 birds was statistically indistinguishable. It is why contingent valuation is treated with suspicion in policy work.
In practice
- A consultation finds residents will pay the same to clean one river as to clean four, and the four include the one.
- A charity appeal raising the same sum whether it names ten beneficiaries or ten thousand is meeting the same insensitivity.