IAI Actuarial Core Principles · Actuarial Statistics · Bayesian inference: priors, posteriors, loss functions and credible intervals
Under quadratic (squared error) loss, the Bayesian estimate of a parameter θ is:
The Bayesian estimate under squared error loss is the posterior mean. Minimising the posterior expected value of (θ - a) squared gives a equal to E[θ | x]. The median corresponds to absolute error loss and the mode to zero-one loss.
- Athe posterior mode
- Bthe posterior meanCorrect
- Cthe posterior median
- Dthe prior mean
- the maximum likelihood estimate
Explanation
Minimising the expected squared error E[(θ - a)^2 | x] gives a = E[θ | x], the posterior mean. The posterior median minimises expected absolute error loss, and the mode corresponds to all-or-nothing (0-1) loss.
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