Introduction
Table 5: TOEFL11Subset Classification Summary
['[BOLD] Classified as –>', '[BOLD] low', '[BOLD] medium', '[BOLD] high']
As mentioned earlier, both classification and regression experiments were performed on this dataset. The first classification model with this corpus consisted of all the features described in the Features section. This model achieved a classification accuracy of 73.2%. It can be seen that the largest confusion exists between low–medium and medium–high and hardly any overlap exists between low and high proficiencies. Consequently, medium proficiency is the most difficult to predict. This is not surprising, and is to be expected, if we remember that language proficiency is a continuum. Further, the confusion matrix works as an evidence that the classification model is actually learning the continuum of relationship between low/medium/high proficiencies.