Shown are the typical approach and our modified approach that includes semi-automated abstract screening on the left and right-hand, respectively (see text for details). In the modified approach the reviewers train and use a classification model to exclude completely "irrelevant" citations ("Level 1a"). They will trust the model's exclusions, and will review only the citations suggested by the classification model.
Wallace et al. BMC Bioinformatics 2010 11:55 doi:10.1186/1471-2105-11-55