Table 3

Formula for calculating retrieval performance parameters for search strategies*

Manual review

Search terms

Meets criteria (unique, relevant CPGs)

Does not meet criteria (non-relevant CPGs or duplicates)

Detected

a

b

Not detected

c

d

*Following the methodology of the Hedges group (see text): sensitivity = a/(a+c); specificity = d/(b+d); precision = a/(a+b); total sample (all unscreened reviewed retrievals) = a+b+c+d; NNR = 1/precision.

CPG = clinical practice guideline.

Haase et al. BMC Medical Research Methodology 2007 7:28   doi:10.1186/1471-2288-7-28