PTT is an electronic bulletin board system that provides a social platform for academic purposes. The system consists of numerous virtual “boards”, each with a different topic, so that a user can find and focus on one specific topic at a time. For example, the “Movie” board provides a space for users to discuss various aspects of movies. There is even a convention where the title of a post may contain the phrase “positive spoiler,” which indicates that this post contains spoilers and positive comments of a movie. Meanwhile, the phrase “negative spoiler” in the title suggests that the author of this post does not recommend this movie. Thus, we can conveniently construct our movie review corpus based on these key phrases. We collected 4,528 posts from 2004 to July, 2016, of which 2,264 are positive and the others negative.