The Concept Repetition model (which is composed of the Concept Repetition, Certainty and Correctness features) was especially useful, as it led to a policy that outperformed the Baseline 1 model, even when we take into account the uncertainty in the model estimates caused by data sparsity.
for the Baseline 2, Percent Correctness, and Frustration models, the estimates for the expected cumulative reward are much less reliable, and no conclusion can be reliably drawn about the usefulness of these features.