Table 6.5Likelihood Ratio Calculation of Posttest Odds

Pretest prevalence of diseasePretest odds of diseasePosttest odds of disease
.01.01:1.04:1
.05.05:1.20:1
.10.11:1.42:1
.15.18:1.66:
.20.25:1.94:1
.25.33:11.25:1
.30.43:11.61:1
.35.54:12.02:1
.40.67:12.50:1
.45.82:13.07:1
.501.00:13.75:1
.551.22:14.58:1

Test sensitivity = .75.

Test specificity = .80.

Likelihood ratio = TP/FP = .75/1 − .80 = 3.75.

From: Chapter 6, Sensitivity, Specificity, and Predictive Value

Cover of Clinical Methods
Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition.
Walker HK, Hall WD, Hurst JW, editors.
Boston: Butterworths; 1990.
Copyright © 1990, Butterworth Publishers, a division of Reed Publishing.

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