手法を比較

	Alliance Portfolio Similarity	Expected Utility Model of War
分野	International Relations	International Relations
系統	Process / pipeline	MCDM
提唱年	1999	1981
提唱者	Bueno de Mesquita (Tau-b); Curtis Signorino & Jeffrey Ritter (S)	Bruce Bueno de Mesquita
種類	Dyadic similarity index over alliance commitment profiles	Formal rational-choice model of conflict initiation
原典	Signorino, C. S., & Ritter, J. M. (1999). Tau-b or not Tau-b: Measuring the similarity of foreign policy positions. International Studies Quarterly, 43(1), 115–144.	Bueno de Mesquita, B. (1981). The War Trap. New Haven, CT: Yale University Press.
別名	Alliance Portfolio Similarity Scores, S-Score of Alliance Similarity, Tau-b Alliance Similarity, Alliance Profile Similarity	Expected Utility Theory of War, The War Trap Model, Rational Choice Model of War Initiation, Expected-Utility Conflict Model
関連	3	3
概要	Alliance portfolio similarity measures how alike two states' overall patterns of alliance commitments are. Each state has a 'portfolio' — the profile of defense pacts, neutrality agreements, ententes, or no tie it holds with every other state — and the similarity of two portfolios is summarized in a single dyadic score. Signorino and Ritter (1999) showed that the long-dominant Kendall's tau-b measure is flawed for this purpose and introduced the S-score as a better-behaved alternative. These scores are a standard proxy for shared interests and have been used to operationalize utilities in expected-utility models of war.	The expected utility model of war, introduced by Bruce Bueno de Mesquita in The War Trap (1981), treats the decision to initiate international conflict as a rational gamble. A leader is modeled as comparing the utility of the outcome they could win against the utility of the outcome they could lose, each weighted by the probability of winning or losing, and is predicted to challenge another state only when this expected utility is positive. It was among the first attempts to derive testable predictions about war initiation from explicit assumptions of rational, utility-maximizing decision making.