  The price of anarchy (PoA) has been widely used in static games to quantify
the loss of efficiency due to noncooperation. Here, we extend this concept to a
general differential games framework. In addition, we introduce the price of
information (PoI) to characterize comparative game performances under different
information structures, as well as the price of cooperation to capture the
extent of benefit or loss a player accrues as a result of altruistic behavior.
We further characterize PoA and PoI for a class of scalar linear quadratic
differential games under open-loop and closed-loop feedback information
structures. We also obtain some explicit bounds on these indices in a large
population regime.
