We give families of examples where sharp rates of convergence to stationarity
of the widely used Gibbs sampler are available. The examples involve standard
exponential families and their conjugate priors. In each case, the transition
operator is explicitly diagonalizable with classical orthogonal polynomials as
eigenfunctions.Comment: This paper commented in: [arXiv:0808.3855], [arXiv:0808.3856],
[arXiv:0808.3859], [arXiv:0808.3861]. Rejoinder in [arXiv:0808.3864].
Published in at http://dx.doi.org/10.1214/07-STS252 the Statistical Science
(http://www.imstat.org/sts/) by the Institute of Mathematical Statistics
(http://www.imstat.org