The number needed to retrieve: A practically useful measure of information retrieval?: Using research in practice

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The article presents information on speculative investigation, the measurement of information retrieval. Systematic reviews increasingly feature on the agenda of the health librarian. For the review team, the concept of appropriateness is important. The denominators for each method are based on an average figure across the review. Each method is compared with all other methods combined, whereas a more useful comparator is head-to-head between competing methods. The availability of suitable data dictates that the chosen review is in an area of complex evidence, making direct comparisons difficult with health technology assessments. This method is potentially more intuitive and helps in advancing discussions about when a particular search method is worth initiating or worth pursuing.

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