Activist Coalitions: Modeling Elections and Regime Change

先前的实证研究建议PI（根据NSF赠款SES 024173），连同一些合作者，已经开发了随机选举模型为英国，以色列，意大利，荷兰和美国。这项工作表明，向选举中心（通常由选举模型预测）的收敛是非常不可能的。在试图解释不收敛，一个正式的模型的基础上外生价。政党领导人或候选人的价值取决于选民对领导人质量的平均评价，基于过去的表现或预期的未来表现。这一理论表明，存在收敛的充分必要条件。如果政党之间的化合价差异足够高（在经验模型的参数给出的精确意义上），则低化合价政党将被迫采取激进立场。该理论解释了戈德华特在1964年美国大选中的立场，以及以色列在1988年，1992年和1996年选举中的政党立场分歧。然而，英国、意大利和荷兰选举的经验模型表明，这些选举中的效价差异不足以解释观察到的分歧。这些结果表明，一个上级选举模式应该包括积极分子对候选人立场的影响。这样一个模型将提供一个更复杂的帐户的政党定位，以回应激进分子的影响。目前的建议涉及的发展和应用的一般随机模型的选举的基础上的假设，有两种价。第一类是固定的或外生的配价，它（如在早期的模型中）被假定为独立于政党地位。然而，由于积极分子为他们所选择的政党提供了关键的时间和金钱资源，政党可以利用这些资源来提高其在选民面前的形象，从而影响其整体价值。在目前的建议中提出的模型中，术语积极分子价被用来表示积极分子资源的效果。这些可以通过媒体等间接影响选民，这样选民就更有可能支持该党。每个政党的问题是，活动家往往比典型的选民更极端。通过选择一个政策立场，以最大限度地提高活动家的支持，党将失去中间派选民。因此，政党必须计算出最佳的边际条件，以最大化选票份额，或其他一些最大值，如选举成功的概率。作为所提出的研究的基础的理论结果是一个（一阶）的平衡条件，它封装了这种权衡的逻辑。此外，由于活动家的支持是以时间和金钱来表示的，因此可以假设活动家的功能将表现出收益递减，从而导致存在一个纳什均衡，其中各方采取最佳立场。然后，这些纳什均衡将取决于激进组织为他们选择的候选人提供资源的意愿。这种模式隐含着在移民、堕胎和支持干细胞研究等领域的政策上发生激进主义冲突的可能性。

Previous empirical research by the proposed PI (under NSF Grant SES 024173), together with a number of collaborators, has developed stochastic electoral models for Britain, Israel, Italy, the Netherlands and the United States. The work suggests that convergence to an electoral center (often predicted by electoral models) is very unlikely. In an attempt to explain non-convergence, a formal model based on exogenous valence was developed. The valence of a party leader or candidate is determined by the average evaluation by the electorate of the quality of the leader, based on past performance, or expected future performance. This theory showed that there were necessary and sufficient conditions for convergence. If the valence difference between the parties was sufficiently high (in a precise sense given by the parameters of the empirical model), the low valence parties would be obliged to adopt radical positions. The theory explained the position of Goldwater in the 1964 US election, as well as divergence of party positions in Israel in the elections of 1988, 1992 and 1996. However, the empirical models of elections in Britain, Italy and the Netherlands indicated that the valence differences in these elections were insufficient to explain the observed divergence. These results suggested that a superior electoral model should incorporate the influence of activists on candidate positions. Such a model would provide a more sophisticated account of party positioning in response to activist influence. The current proposal involves the development and application of a general stochastic model of elections based on the assumption that there are two kinds of valence. The first kind is the fixed or exogenous valence which (as in the earlier model) is assumed to be independent of party position. However, since activists provide crucial resources of time and money to their chosen party, the party can use these resources to enhance its image before the electorate, thus affecting its overall valence. In the model presented in the current proposal, the term activist valence is used to denote the effect of activist resources. These can indirectly influence voters, through the media etc., so that voters become more likely to support the party. The problem for each party is that activists tend to be more extreme than the typical voter. By choosing a policy position to maximize activist support, the party will lose centrist voters. The party must therefore calculate the optimal marginal condition to maximize vote share, or some other maximand such as probability of electoral success. The theoretical result used as the basis for the proposed research is a (first order) balance condition which encapsulates the logic of this trade off. Moreover, because activist support is denominated in terms of time and money, it can be assumed that the activist functions will exhibit decreasing returns, leading to existence of a Nash equilibrium where parties adopt optimal positions. These Nash equilibria will then depend on the willingness of activist groups to provide resources for their chosen candidates. Implicit in this model is the possibility of activist conflict over the policies in areas such as immigration, abortion, and support for stem cell research.