a specification of which parameters are to be plotted,
a vector of names are the only legal values. If missing, all parameters are considered.
probs
a vector of specified quantiles, by default, the c(0.025,0.5,0.975) are ("probs")
Value
A matrix with quantiles on the rows, with number of rows specified as length of the probs vector for the specified quantiles, with covariates on the columns