A New Approach for Estimating the Policy Positions of Parties and Districts Based on the Spatial Voting Theory‥‥Theoretical and Empirical Analysis

我指出，在选举中的政治行动者的经验唐氏政策位置自然是由政党（候选人）获得的选票数决定的。我开发了一个系统来进行这种计算。我将其应用于日本和英国的全国选举（即，英国的一部分）。结果表明，在唐氏意义上的选举的主要问题是城市=农村冲突和失业问题，分别在日本和英国。在日本的例子中，如果采用Downsian框架，结果表明意识形态不是选举的主要因素。但在我的方法中，有几个技术问题。首先，需要在高维空间中进行函数的全局优化，因此必须非常小心地获得正确的全局最优值。在本研究中，我成功地在可接受的计算时间内得到了这个问题的看似正确的解决方案。第二，在我的方法中，需要对每个区域上的密度形状进行先验假设。作为第一近似，我使用正常密度。这里一个自然的问题是，结果是否对选择敏感。我检查了结果几乎保持不变，如果我们改变t-分布，而不是正常的。第三，我们没有使用有关各方政策的先验信息。因此，除了Downsian机制之外，由于噪声或其他因素，各方的顺序可能随着时间的推移而不稳定地变化。我发现无论是在日本还是在英国，结果都非常稳定，因此我的方法现在实际上适用于全国选举。在研究过程中，我遇到了选举数据缺乏的麻烦。因此，我安排了数据库，这是向公众开放。人们可以通过互联网访问数据。这是本研究的另一个贡献。

I point out that the empirical Downsian policy locations of political actors in an election are naturally determined from the number of votes gained by the parties (candidates). I developed a system for carrying out this calculation. I applied it to the national elections of Japan and England (i.e., a part of the United Kingdom.). The results show that the main issues of elections in the Downsian sense are urban=rural conflicts and the jobless problem, respectively, in Japan and in England. In the case of Japan, the result shows that the ideology is not the main factor of the election if we take the Downsian frame.In my approach, however, there are several technical problems.First, global optimization of a function in a high dimensional space is needed, so that one must be very careful in getting the correct global optimum. In this research I succeeded in getting seemingly correct solution to this problem within a acceptable computation time.Second, an a priori assumption on the shape of density on each district is needed in my approach. As a first approximation, I use the normal density. A natural question here is whether the result is sensitive to the choice or not. I checked that the results remains almost as it is if we change the t-distribution instead of the normal.Third, we use no prior information on the policy of parties. Thus it is possible that the order of parties changes unstable over time caused by noises or factors other than the Downsian mechanisms. I found that the results are very stable over time both in Japan and in England.Thus my approach is now practically applicable to national elections.In the process of research, I encountered a trouble of the lack of election data. Thus I arranged the database which is open to public. One can access the data through internet. It is another contribution of this research.