Exploring the Microscopic Textual Characteristics of Japanese Prime Ministers’ Diet Addresses by Measuring the Quantity and Diversity of Nouns

Exploring the Microscopic Textual Characteristics of Japanese Prime Ministers' Diet Addresses by Measuring the Quantity and Diversity of Nouns* Takafumi Suzuki1 and Kyo Kageura2 1Graduate School of Interdisciplinary Information Studies, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Japan qq16116@iii.u-tokyo.ac.jp 2Graduate School of Education, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Japan kyo@p.u-tokyo.ac.jp Abstract. This study explores the textual characteristics, more precisely the quantity and diversity of nouns, of Japanese prime ministers' Diet addresses. In the field of stylistics, textual characteristics independent of the content have been examined with the aim on detecting the authors, genres, and chronological variations of texts. This study focuses instead on textual characteristics related to the content of texts, namely the quantity and diversity of nouns, because our aim is to analyze texts to better understand two political phenomena: (a) the difference between the two types of Diet addresses delivered by Japanese prime ministers, and (b) the perceived changes made to these addresses by two powerful prime ministers. It is a case study of the microscopic characterization of texts, which has become more and more important with the expansion in the scope of stylistics and the production of a wide variety of new types of texts following the advent of the Web. Keywords: Japanese prime ministers' speeches, quantity and diversity of nouns, microscopic textual characteristics, Monte Carlo simulation 1. Introduction In the field of stylistics, as computational approaches have been developed and many on-line corpora have been constructed, statistical textual characteristics have been systematically examined. These textual characteristics have traditionally been used for detecting the authors, registers, and chronological variations of texts. Recently, they have also been used for more practical applications such as spam filtering (Argamon, Whitelaw, Chase, Raj Hota, Garg, and Levitan, 2007). With this expansion in the scope of stylistics and the production of a wide variety of new types of texts especially with the growth of the Web (Aitchison and Lewis, 2003), the microscopic characterization of different types of texts has become more and more important. Turning our eyes to the field of political science, the content of political speeches is regarded as important for analyzing the policies, attitudes and thoughts of political actors (Axelrod, 1976). Among such speeches, prime ministers' Diet addresses are recognized as the most * This study was supported by a Suntory Foundation Research Grant, 2007-2008. We would like to express our gratitude for this support. An earlier version of this study was presented at the 35th annual meeting of the Behaviormetric Society of Japan. We would like to thank the participants for their useful comments. Copyright 2007 by Takafumi Suzuki and Kyo Kageura 459 important material for understanding Japanese politics as they reflect Japanese governmental policies, and prime ministerial attitudes and thoughts (Watanabe, 1974; Kusano, 2005). As the role of the media and the performance of politicians increase in importance in contemporary politics (Kusano, 2006), the style of prime ministers' speeches, as well as their content, have attracted more attention (Ahrens, 2005; Azuma, 2006). Against this background, this study …

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