sumo wrestling matches, along with the effect that allegations of corruption have on match results, to conclude that those who already have eight wins collude with those who are 7–7 and let them win, since they have already secured their position for the following tournament. Despite condemnation of the claims by the Japan Sumo Association following the book's publication in 2005, the 2011 Grand Tournament in Tokyo was canceled for the first time since 1946 because of allegations of match-fixing. The authors attempt to demonstrate the power of data mining, as a number of their results emerge from Levitt's analysis of various databases. The authors posit that various incentives encourage teachers to cheat by assisting their students with multiple-choice high-stakes tests. Such cheating in the Chicago school system is inferred from detailed analysis of students' answers to multiple-choice questions. Levitt asks, "What would the pattern of answers look like if the teacher cheated?", and hypothesizes that the more difficult questions found at the end of test sections will be answered correctly more frequently than the easy questions at the beginning of test sections. Second edition In Chapter 2 of Freakonomics, the authors wrote of their visit to folklorist Stetson Kennedy's Florida home where the topic of Kennedy's investigations of the Ku Klux Klan were discussed. However, in their January 8, 2006, column in The New York Times Magazine, Dubner and Levitt wrote of questions about Stetson Kennedy's research ("Hoodwinked", pp. 26–28) leading to the conclusion that Kennedy's research was at times embellished for effectiveness. In the "Revised and Expanded Edition" this embellishment was noted and corrected: "Several months after Freakonomics was first published, it was brought to our attention that this man's portrayal of his crusade, and various other Klan matters, was considerably overstated ... we felt it was important to set straight the historical record." Criticism Freakonomics has been criticized for being a work of sociology or criminology, rather than economics. Israeli economist Ariel Rubinstein criticized the book for making use of dubious statistics and complained that "economists like Levitt ... have swaggered off into other fields", saying that the "connection to economics ... [is] none" and that the book is an example of "academic imperialism". Arnold Kling has suggested the book is an example of "amateur sociology". The impact of legalized abortion on crime Revisiting a question first studied empirically in the 1960s, Donohue and Levitt argue that