(This article was originally published at R – Xi'an's Og, and syndicated at StatsBlogs.)

**A** definitely puzzled participant on X validated, confusing the Normal variate or variable used in the random walk Metropolis-Hastings step with its Normal density… It took some cumulated efforts to point out the distinction. Especially as the originator of the question had a rather strong a priori about his or her background:

“I take issue with your assumption that advice on the Metropolis Algorithm is useless to me because of my ignorance of variates. I am currently taking an experimental course on Bayesian data inference and I’m enjoying it very much, i believe i have a relatively good understanding of the algorithm, but i was unclear about this specific.”

despite pondering the meaning of the call to rnorm(1)… I will keep this question in store to use in class when I teach Metropolis-Hastings in a couple of weeks.

Filed under: Books, Kids, R, Statistics, University life Tagged: cross validated, Gaussian random walk, Markov chain Monte Carlo algorithm, MCMC, Metropolis-Hastings algorithm, Monte Carlo Statistical Methods, normal distribution, normal generator, random variates

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