of interest in reviews is the reliability of each party, not the quality of a good. Reliability
ratings are conveyed through the numbers of positive and negative feedback reports that a
user has received. The most documented effect of this review regime is the impact of a
seller’s overall rating (given by buyers) on the sale price. One particular challenge to esti-
mating this effect is that goods sold on eBay vary in their condition, and in small (but
significant) characteristics that are difficult to observe by the econometrician. For exam-
ple, books of the same title might be heavily used, lightly used, or brand new; they might
be a domestic or international edition; they might have highlighter marks or dog-eared
pages. Looking at data from