This study proposes an index of representativeness for analyzing the characteristics of academic paper categories. Many textual indices have been proposed in the field of computational stylistics, but all of the previous indices are limited in that they (a) focus only on the styles of the texts; (b) return an absolute value for every text, and (c) are based on the number of tokens. In this study, we propose an index of representativeness that does not have the weaknesses of the previous indices. Our index is based on the h-index that was originally proposed in the field of scientometrics. We redefine it here for textual data. We show the effectiveness of our index for analyzing the characteristics that differ between four genres and three subfields in Japanese academic papers. © 2011 by Takafumi Suzuki, Kiyoko Uchiyama, Ryota Tomisaka, and Akiko Aizawa.