TO INTERVENE OR NOT TO INTERVENE - A BIASED DECISION

Alliances are related to the occurrence of conflict. A theoretical mod el predicts how alliance reliability affects the occurrence of conflic t in the international system. Suppose that two nations are at war. Th e intervention of a third nation into this war affects the likely outc ome. Nations prefer to fight wars that they expect to win. Nations are more likely to involve themselves in wars in which they anticipate al lied support. Estimates of alliance reliability are obtained and used to demonstrate that nations consider alliance reliability when decidin g whether to become involved in conflict. For example, nations with un reliable allies are more likely to surrender if attacked than are nati ons with reliable allies. Alliance reliability affects the occurrence of war. Unfortunately, whether an alliance is honored is only observab le when a war actually occurs. The author discusses the sampling bias that this creates.