Finding the best available evidence: how can we know?
Hayman, Sarah L
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The importance (in all scientific fields) of finding and using evidence is growing rapidly, with increased recognition that decisions should be based on sound evidence. Key to finding this evidence is effective searching. Alongside this imperative, the searching context is becoming more complex. The number of articles indexed is enormous and increasing. In the medical field, PubMed contains over 24 million citations with over 1 million entered in 2014. Effective searching requires an understanding of database mechanisms and the terminology (including associated thesauri) of each subject. Searchers need an understanding of the requirements of the end user: what is considered relevant and what are the levels of evidence? We suggest that a scientific approach be taken to the searching process, to ensure that the best available evidence is found, and that search methodology is tested and validated. What methods can we employ to indicate what we might have missed in our search? Search results should be tested and results fed back into the search, to improve searching effectiveness and thereby outcomes for the end user. Search filters are validated search strategies, created using known methodology, for a given bibliographic database. The relevant terminology and database mechanisms are built into a strategy that is created from, and tested against, subsets of a gold standard set of references. Results are screened by external reviewers with expert subject knowledge, to minimise bias. The search filter performance is rated for precision and sensitivity, to provide known effectiveness in a standard set that can be extrapolated to open search. Details of the methodology and the filter performance are published for transparency. CareSearch and Flinders Filters have developed a number of subject-based search filters. This paper discusses the importance of evidence-based searching; how these search filters are developed and lessons for general searching in scientific literature.