Open Access Research article

An alternative to the hand searching gold standard: validating methodological search filters using relative recall

Margaret Sampson1*, Li Zhang12, Andra Morrison13, Nicholas J Barrowman145, Tammy J Clifford156, Robert W Platt7, Terry P Klassen8 and David Moher156

Author Affiliations

1 Chalmers Research Group, Children's Hospital of Eastern Ontario Research Institute, Canada

2 Natural Sciences Library, University of Saskatchewan, Saskatoon, Canada

3 Canadian Agency for Drugs and Technologies, Ottawa, Canada

4 School of Mathematics and Statistics, Carleton University, Ottawa, ON, Canada

5 Department of Pediatrics, University of Ottawa, Ottawa, ON, Canada

6 Department of Epidemiology and Community Medicine, University of Ottawa, Ottawa, ON, Canada

7 Departments of Pediatrics and of Epidemiology and Biostatistics, McGill University, Montreal, PQ, Canada

8 Alberta Research Center for Child Health Evidence, Department of Pediatrics, University of Alberta

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BMC Medical Research Methodology 2006, 6:33  doi:10.1186/1471-2288-6-33

Published: 18 July 2006



Search filters or hedges play an important role in evidence-based medicine but their development depends on the availability of a "gold standard" – a reference standard against which to establish the performance of the filter. We demonstrate the feasibility of using relative recall of included studies from multiple systematic reviews to validate methodological search filters as an alternative to validation against a gold standard formed through hand searching.


We identified 105 Cochrane reviews that used the Highly Sensitive Search Strategy (HSSS), included randomized or quasi-randomized controlled trials, and reported their included studies. We measured the ability of two published and one novel variant of the HSSS to retrieve the MEDLINE-index studies included in these reviews.


The systematic reviews were comprehensive in their searches. 72% of included primary studies were indexed in MEDLINE. Relative recall of the three strategies ranged from .98 to .91 across all reviews and more comprehensive strategies showed higher recall.


An approach using relative recall instead of a hand searching gold standard proved feasible and produced recall figures that were congruent with previously published figures for the HSSS. This technique would permit validation of a methodological filter using a collection of approximately 100 studies of the chosen design drawn from the included studies of multiple systematic reviews that used comprehensive search strategies.