A bayes net toolkit for student modeling in intelligent tutoring systems

  • Authors:

  • Kai-min Chang;Joseph Beck;Jack Mostow;Albert Corbett

  • Affiliations:

  • Project LISTEN, School of Computer Science, Carnegie Mellon University, Pittsburgh, PA;Project LISTEN, School of Computer Science, Carnegie Mellon University, Pittsburgh, PA;Project LISTEN, School of Computer Science, Carnegie Mellon University, Pittsburgh, PA;Project LISTEN, School of Computer Science, Carnegie Mellon University, Pittsburgh, PA

  • Venue:
  • ITS'06 Proceedings of the 8th international conference on Intelligent Tutoring Systems
  • Year:
  • 2006

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Abstract

This paper describes an effort to model a student's changing knowledge state during skill acquisition. Dynamic Bayes Nets (DBNs) provide a powerful way to represent and reason about uncertainty in time series data, and are therefore well-suited to model student knowledge. Many general-purpose Bayes net packages have been implemented and distributed; however, constructing DBNs often involves complicated coding effort. To address this problem, we introduce a tool called BNT-SM. BNT-SM inputs a data set and a compact XML specification of a Bayes net model hypothesized by a researcher to describe causal relationships among student knowledge and observed behavior. BNT-SM generates and executes the code to train and test the model using the Bayes Net Toolbox [1]. Compared to the BNT code it outputs, BNT-SM reduces the number of lines of code required to use a DBN by a factor of 5. In addition to supporting more flexible models, we illustrate how to use BNT-SM to simulate Knowledge Tracing (KT) [2], an established technique for student modeling. The trained DBN does a better job of modeling and predicting student performance than the original KT code (Area Under Curve = 0.610 0.568), due to differences in how it estimates parameters.