Metrics for Automated Review Classification: What Review Data Show

Peer review is only effective if reviews are of high quality. In a large class, it is unrealistic for the course staff to evaluate all reviews, so a scalable assessment mechanism is needed. In an automated system, several metrics can be calculated for each review. One of these metrics is volume, which is simply the number of distinct words used in the review. Another is tone, which can be positive (e.g., praise), negative (e.g., disapproval), or neutral. A third is content, which we divide into three subtypes: summative, advisory, and problem detection. These metrics can be used to rate reviews, either singly or in combination. This paper compares the automated metrics for hundreds of reviews from the Expertiza system with scores manually assigned by the course staff. Almost all of the automatic metrics are positively correlated with manually assigned scores, but many of the correlations are weak. Another issue is how the review rubric influences review content. A more detailed rubric draws the reviewer's attention to more characteristics of an author's work. But ultimately, the author will benefit most from advisory or problem detection review text. And filling out a long rubric may distract the reviewer from providing textual feedback to the author. The data fail to show clear evidence that this effect occurs.