Automatic assessment of easiness of Japanese for writing aid of “Easy Japanese”

In this paper, we developed a method to assess easiness of a Japanese sentence for a non-native speaker of Japanese. This method is intended to be used as a writing aid of Easy Japanese (EJ), which is used as a language to convey information to foreigners in Japan under emergency condition such as earthquake. We examined six features (number of words, nouns, verbs, phrases, and loanwords in the sentence, and the average grade of words in the sentence) as features, and used linear regression model to combine the features. As a result of evaluation experiment, we obtained correlation coefficient of 0.55 between the predicted scores and the easiness scores given by human subjects.