Pixel International Conferences

Since 2007, we have been engaged in developing readability indices attuned to the English textbooks based on the English Course of Study in Japan, and have developed readability indices, Ozasa-Fukui Year Level, Ver. 1, 2 and 2.1.  However, the Course of Study was revised and put into force from 2012 on, which made it necessary to update these English readability indices.  This paper reports a project that aims to develop a new readability index, Ver. 3.4.1nhnc1-5wus, which is attuned to the new English teaching system of Japan,.  In the first phase, two sets of commonly used Japanese English textbooks were digitized in order to develop readability criteria, textbook-based word dictionary and textbook-based idiom dictionary.  In the second phase, first, a multiple regression analysis and a linear analysis were computed, using sentence length, word length, textbook-based word difficulty and textbook-based idiom difficulty as independent variables and the year of passages as a dependent variable, which yielded a linear function (Diff).  Then, non-linear analyses were computed, using experts’ readability judgment of selected English sentences as a dependent variable and the obtained linear function (Diff) as an independent variable.  The computation yielded a non-linear function expression for Ver. 3.4.1nhnc1-5wus with an unexpectedly low explanation rate: 

Ver. 3.4.1nhnc1-5wus =  4.1026*exp (-123.3438*0.1709^Diff)+1

Diff = 0.0915*Words+0.5621*Syllables+1.6230*WordDiff+0.0822*IdiomDiff-0.2836

 (r^2 = 0.6400)