This may be used to plot a juxtaposition of MCMC algorithms according
  either to IAT or ISM (Independent Samples per Minute).
# S3 method for juxtapose
plot(x, Style="ISM", …)This required argument is an object of class
    juxtapose.
This argument accepts either IAT or ISM,
    and defaults to ISM.
Additional arguments are unused.
When Style="IAT", the medians and 95% probability intervals of
  the integrated autocorrelation times (IATs) of MCMC algorithms are
  displayed in a caterpillar plot. The best, or least inefficient, MCMC
  algorithm is the algorithm with the lowest IAT.
When Style="ISM", the medians and 95% probability intervals of
  the numbers of independent samples per minute (ISM) of MCMC algorithms
  are displayed in a caterpillar plot. The best, or least inefficient,
  MCMC algorithm is the algorithm with the highest ISM.
For more information, see the Juxtapose function.