The Impact of Data Quantity and Source on the Quality of Data-Driven Hints for Programming

In the domain of programming, intelligent tutoring systems increasingly employ data-driven methods to automate hint generation. Evaluations of these systems have largely focused on whether they can reliably provide hints for most students, and how much data is needed to do so, rather than how useful the resulting hints are to students. We present a method for evaluating the quality of data-driven hints and how their quality is impacted by the data used to generate them. Using two datasets, we investigate how the quantity of data and the source of data (whether it comes from students or experts) impact one hint generation algorithm. We find that with student training data, hint quality stops improving after 15-20 training solutions and can decrease with additional data. We also find that student data outperforms a single expert solution but that a comprehensive set of expert solutions generally performs best.