Comparing the performance of narrow vs. broad search strategies when using machine learning-based software for title/abstract screening

Objectives: To retrospectively evaluate workload implications and recall performance of narrower or broader database search strategies when using active learning screening tools. Method: A convenience sample of 10 completed reviews was used to assess search strategy performance in ASReview LAB, an open-source systematic review software tool. For each review, a single database search strategy was selected and then revised to either broaden (n = 9) or narrow (n = 1) the scope. Results from both the more sensitive (broader) and more precise (narrower) search strategies were labeled as relevant or irrelevant based on inclusion in the completed review. The labeled result sets were uploaded into the ASReview LAB simulation module, which mimics the process of human screening. Metrics such as number of records screened to reach recall of 95% or more were recorded. The effects of three different stopping rules on workload and recall were also explored. Results: For quantitative systematic reviews, the difference in absolute screening time required to reach 95% recall between broader or narrower search strategies was minimal (≤35 minutes). In contrast, for qualitative systematic reviews and other review types, broader search strategies led to increased workload. With respect to stopping rules, the time-based stopping heuristic resulted in substantial workload increases when broader search strategies were employed. Conclusion: Time savings achieved through the use of semi-automated screening tools may not always offset additional screening time required by broader, more sensitive search strategies. Librarians and information specialists should consider a variety of factors when determining the appropriate balance between search sensitivity and specificity in the context of semi-automated screening tools.