Objective: The purpose of this study was to investigate the relative effectiveness of three web-scale discovery (WSD) tools in answering health sciences search queries.Methods: Simple keyword searches, based on topics from six health sciences disciplines, were run at multiple real-world implementations of EBSCO Discovery Service (EDS), Ex Libris's Primo, and ProQuest's Summon. Each WSD tool was evaluated in its ability to retrieve relevant results and in its coverage of MEDLINE content.Results: All WSD tools returned between 50%-60% relevant results. Primo returned a higher number of duplicate results than the other 2 WSD products. Summon results were more relevant when search terms were automatically mapped to controlled vocabulary. EDS indexed the largest number of MEDLINE citations, followed closely by Summon. Additionally, keyword searches in all 3 WSD tools retrieved relevant material that was not found with precision (Medical Subject Headings) searches in MEDLINE.Conclusions: None of the 3 WSD products studied was overwhelmingly more effective in returning relevant results. While difficult to place the figure of 50%-60% relevance in context, it implies a strong likelihood that the average user would be able to find satisfactory sources on the first page of search results using a rudimentary keyword search. The discovery of additional relevant material beyond that retrieved from MEDLINE indicates WSD tools' value as a supplement to traditional resources for health sciences researchers.

Background: Librarians often teach evidence-based practice (EBP) within health sciences curricula. It is not known what teaching methods are most effective.