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Table 1 Contingency table comparing filter to ‘reference set’ and explanation of statistical descriptions

From: Paramedic literature search filters: optimised for clinicians and academics

Filter

Manual review of each article

 
 

Paramedic articles

Non-paramedic articles

 

Article identified

a

b

a + b

Article not identified

c

d

c + d

 

a + c

b + d

a + b + c + d

  1. Caption: Sensitivity = a/(a + c): proportion of all articles relevant to paramedics in the reference set that are retrieved by the filter. Specificity = d/(b + d): proportion of all articles not relevant to paramedics in the reference set that are correctly not retrieved by the filter. Precision = a/(a + b). NNR = 1/precision: the number of relevant and non-relevant articles that need to be screened in order to find one of relevance