a) Which parameter mixes best according to Neff in the output? (b) Which parameter mixes worst according to Neff in the output? (c) Give a 95 % posterior interval for the degrees-of-freedom...

a) Which parameter mixes best according to Neff in the output?

(b) Which parameter mixes worst according to Neff in the output?

(c) Give a 95 % posterior interval for the degrees-of-freedom parameter.

Next, plot the results to check for convergence to the stationary distribution (posterior distribution) using Gelman plots and trace plots.

Plotting the ACFs gives much insight into how well the chains are mixing. The less autocorrelation, the better. The function autocorr.plot() plots ACFs separately for each chain.