Positive political theory or explanatory political theory is the study of politics using formal methods such as social choice theory, game theory, and statistical analysis. In particular, social choice theoretic methods are often used to describe and (axiomatically) analyze the performance of rules or institutions. The outcomes of the rules or institutions described are then analyzed by game theory, where the individuals/parties/nations involved in a given interaction are modeled as rational agents playing a game, guided by self-interest. Based on this assumption, the outcome of the interactions can be predicted as an equilibrium of the game. Positive political theory or explanatory political theory is the study of politics using formal methods such as social choice theory, game theory, and statistical analysis. In particular, social choice theoretic methods are often used to describe and (axiomatically) analyze the performance of rules or institutions. The outcomes of the rules or institutions described are then analyzed by game theory, where the individuals/parties/nations involved in a given interaction are modeled as rational agents playing a game, guided by self-interest. Based on this assumption, the outcome of the interactions can be predicted as an equilibrium of the game. The founder of the field was William H. Riker. In his book The Theory of Political Coalitions (1962), he applied the principles of game theory to the study of politics.