Assessing the accuracy of the most popular legal citators

In this new study, Professor Paul Hellyer (William & Mary) evaluates and compares the accuracy of the three leading legal citators - West's Keycite, Lexis' Shepards, and Bloomberg's Bcite. Professor Hellyer's study is called Evaluating Shepard's, KeyCite and BCite for Case Validation Accuracy and can be found at 110 Law Libr. J. 449 (2018). From the abstract:

This study evaluates and compares how accurately three legal citators (Shepard's, KeyCite, and BCite) identify negative treatment of case law, based on a review of 357 citing relationships that at least one citator labeled as negative. In this sample, Shepard's and KeyCite missed or mislabeled about one-third of negative citing relationships, while BCite missed or mislabeled over two-thirds. The citators' relative performance is less clear when examining the most serious citator errors, examples of which can be found in all three citators.

(jbl).