Vickrey was awarded the prize jointly with James Mirrlees for research into the economic theory of incentives under asymmetric information. An example of this is the situation where for instance, the insured know more about their health than their insurer.
He also did important work in congestion pricing, the idea that roads and other services should be priced so that users see the costs that arise from the service being fully used when there is still demand. Congestion pricing gives a signal to users to adjust their behaviour or to investors to expand the service in order to remove the constraint. His theory was later partially put into action in the City of London (England).
