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Table 7 Formulae for calculating the sensitivity, specificity, precision, and accuracy of searches for detecting sound clinical studies

From: An overview of the design and methods for retrieving high-quality studies for clinical care

   Manual Review (Hand search)
   Meets Criteria Does Not Meet Criteria
Search Terms Detected a b
  Not detected c d
   a + c b + d
  1. a = true positives, articles found by the search term meet the criteria for purpose category (e.g., treatment) and methodologic rigor (i.e., "pass")
  2. b = false positives, articles found by the search term do not meet the criteria for purpose category and methodologic rigor
  3. c = false negatives, articles not found by the search term but did meet the criteria for purpose category and methodologic rigor
  4. d = true negatives, articles not found by the search term and did not meet the criteria for purpose category and methodologic rigor
  5. Sensitivity = a/(a+c); Precision = a/(a+b); Specificity = d/(b+d);
  6. Accuracy = (a+d)/(a+b+c+d).
  7. All articles classified during the manual review of the literature, n = (a+b+c+d).