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What do trace plots tell us?
The trace plot, sometimes called a time-series plot, shows the sampled values of a parameter over time. This plot helps you to judge how quickly the MCMC procedure converges in distribution—that is, how quickly it forgets its starting values.
What is MCMC trace plot?
Trace plots provide an important tool for assessing mixing of a chain. Density plots are smoothed histograms of the samples, that is they show the function that we are trying to explore. We can get trace and density plots for all variables in an MCMC trace using plot .
How to highlight a chain in MCMC trace?
For mcmc_trace_highlight (), passed to ggplot2::geom_point () to control the transparency of the points for the chains not highlighted. For mcmc_trace_highlight (), an integer specifying one of the chains that will be more visible than the others in the plot.
What does a trace plot of parameters indicate?
What does a trace plot of parameters indicate? You create the parameter trace plots to make sure that your a priori distribution is well calibrated which is indicated by your parameters having sufficient state changes as the MCMC algorithm runs. An extreme example is that you set your a priori distribution variance at 0.
Which is the vignette plotting package for MCMC?
Plots of parameter estimates from MCMC draws are covered in the separate vignette Plotting MCMC draws, and graphical posterior predictive model checking is covered in the Graphical posterior predictive checks vignette. Note that most of these plots can also be browsed interactively using the shinystan package.
What kind of problem do MCMC diagnostics try to spot?
When we run an MCMC algorithm for periods, we get an MCMC sample made up of the first realizations of the chain: and then we use the empirical distribution of the sample to approximate the target distribution. What kind of problems do MCMC diagnostics try to spot?