Past exam of the statistics course of the University of Oxford / 2023 / 3 / a / i / Solution

Given the observed data, a $100(1-\alpha )\%$ credible interval $[a,b]$ for the scalar parameter satisfiesThe probability refers to the posterior distribution, proportional to $\pi (\theta ){\prod }_{i}f(x_i\mid \theta )$ on the parameter space. It conditions on the observations; it is not the repeated-sampling coverage probability definition of a confidence interval.