= Sensitivity × Prevalence + Specificity × (1 − Prevalence)
Accuracy: overall probability that a patient is correctly classified. Negative predictive value: probability that the disease is not present when the test is negative. Positive predictive value: probability that the disease is present when the test is positive. = False negative rate / True negative rate = (1-Sensitivity) / Specificity Negative likelihood ratio: ratio between the probability of a negative test result given the presence of the disease and the probability of a negative test result given the absence of the disease, i.e. = True positive rate / False positive rate = Sensitivity / (1-Specificity) Positive likelihood ratio: ratio between the probability of a positive test result given the presence of the disease and the probability of a positive test result given the absence of the disease, i.e. Specificity: probability that a test result will be negative when the disease is not present (true negative rate). Sensitivity: probability that a test result will be positive when the disease is present (true positive rate). (Version 22.(*) These values are dependent on disease prevalence. Sheskin DJ (2004) Handbook of parametric and nonparametric statistical procedures. Parshall MB (2013) Unpacking the 2 x 2 table. Pagano M, Gauvreau K (2000) Principles of biostatistics. Kirkwood BR, Sterne JAC (2003) Essential medical statistics, 2 nd ed. Deeks JJ, Higgins JPT (2010) Statistical algorithms in Review Manager 5. 
Odds ratios should be avoided when events are common.
Altman DG (1991) Practical statistics for medical research.A standard normal deviate ( z-value) is calculated as ln(OR)/SE, and the P-value is the area of the normal distribution that falls outside ± z (see Values of the Normal distribution table). Test of significance: the P-value is calculated according to Sheskin, 2004 (p. Where zeros cause problems with computation of the odds ratio or its standard error, 0.5 is added to all cells (a, b, c, d) (Pagano & Gauvreau, 2000 Deeks & Higgins, 2010). With the standard error of the log odds ratio being The odds ratio (OR), its standard error and 95% confidence interval are calculated according to Altman, 1991.
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