Measuring Competitiveness and Cooperativeness

We develop an index of competitiveness and cooperativeness which is based on the primitives of a normal-form game, i.e. players, strategies and payoffs. The index relies on a unique decomposition of a given game into a zero-sum game and a common-interest game. The index decreases in the distance to its zero-sum part and it increases in the distance to its common-interest part. Alternatively, the index increases if the share of variation in payoffs captured by the zero-sum part increases We compute our index for well-known classes of games such as Prisoner's Dilemma,games with Strategic Complements and Substitutes, All-pay auctions, Tullock contests, and Public Goods games. The comparative statics of our index coincide with economic intuition. The index does well in explaining experimental