How Challenging are Bebras Tasks? : An IRT Analysis Based on the Performance of Italian Students

This paper analyses the results of the 2014 edition of the Italian Bebras/Kangourou contest, exploiting the Item Response Theory statistical methodology in order to infer the difficulty of each of the proposed tasks starting from the scores attained by the participants. Such kind of analysis, enabling the organizers of the contest to check whether or not the difficulty perceived by pupils was substantially different from that estimated by those who proposed the tasks, is important as a feedback in order to gain knowledge to be used both in ranking participants and in organizing future editions of the contest. We show how the proposed analysis essentially highlights that the 63% of tasks was perceived at the same level of difficulty estimated by those who proposed them, but a 37% of tasks were either easier or more difficult than expected.