Burn-in

Burn-in

Type Topic
Taught in Markov chains, Gibbs sampling, and Metropolis–Hastings · Bayesian linear regression
Part Bayesian statistics
Questions using it 13

The initial stretch of a Markov chain Monte Carlo run that is discarded because the chain may not yet have forgotten its starting value; the course also calls it warm-up. Discarding it limits dependence on the start. It does not prove that the rest of the run has converged.

In Markov chains, Gibbs sampling, and Metropolis–Hastings

Discarding early draws is called warm-up or burn-in. It limits dependence on the chosen initial state, but it is not a proof of convergence. Strong posterior correlation produces staircase-like Gibbs paths and high autocorrelation. Separated modes are harder still because a coordinate-wise move may have to cross a low-density barrier.

In Bayesian linear regression

The resulting pairs are iid joint-posterior draws. There is no burn-in, serial dependence, or convergence diagnostic.

Used in

See also

Warm-up is not a convergence proof · Direct posterior simulation · Markov chain · Stationarity and detailed balance · Detailed balance implies stationarity · Systematic-scan Gibbs sampler · Metropolis–Hastings update · Metropolis–Hastings invariance

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