Metering problems sometimes can be
resolved well through the exchange of
products across competitive markets, because
in many situations markets yield a
high correlation between rewards and
productivity. If a farmer increases his output
of wheat by 10 percent at the prevailing
market price, his receipts also increase
by 10 percent. This method of organizing
economic activity meters the
output directly, reveals the marginal product
and apportions the rewards to resource
owners in accord with that direct
measurement of their outputs. The success
of this decentralized, market exchange in
promoting productive specialization requires
that changes in market rewards fall
on those responsible for changes in output.