Figure 4From: Boolean versus ranked querying for biomedical systematic reviews Recall of Boolean queries after re-running on Ovid MEDLINE (1950-Nov week 3, 2008). Average recall for (a) original queries (upper) are 0.27 and 0.29 for Tier 1 and Tier 2, respectively, and for (b) simplified queries (lower) are 0.79 and 0.82.Back to article page