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Figure 2 Bayesian analysis of a representative clinical megatrial (5). The curve labeled "Prior" represents the operative prior distribution for log odds ratio (OR) (x_p = 0, _p = 0.07); the curve labeled "Evidence" represents the distribution for log OR based on the empirical data (x_e = –0.12, _e = 0.06); and the curve labeled "Posterior" represents the distribution for log OR derived from the product of the prior and the evidence (x_pe = –0.07, _pe = 0.05). The smaller the standard deviation, the narrower is the distribution and the greater is its information content and precision. All curves are normalized to the same unit area. Probabilities for any magnitude of response can be computed directly in terms of the area under the appropriate region of the posterior distribution. The conventional (one-tailed) p value is represented by the proportion of the evidentiary distribution to the right of zero (here, 0.021).

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