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Likelihood ratio, skull roentgenograms, and clinical decision-making.

To the Editor.—
 In the February 1982 issue of Pediatrics, Leonidas et al1 examined the relationship between clinical findings and skull fractures in children evaluated with skull roentgenograms to develop reliable criteria for the ordering of roentgenograms in patients with head trauma. In their analysis, the authors used the liklihood ratio (LR) to characterize quantitatively the relationship between a clinical finding and the presence of a skull fracture. As defined by the authors, the LR is that ratio between the probability of a certain clinical finding occurring in the presence of a fracture and the probability of the same clinical finding occurring in the absence of a fracture.