plot.ssym produces the graph in which the goodness-of-fit statistic \(\Upsilon\) is based.
This function also displays graphs of the deviance-type residuals versus the fitted values for the median and the skewness (or the relative dispersion) submodels.
Under the presence of an uncensored sample, the function plot()
produces a graph of the standardized individual-specific weights versus the ordinary residuals (i.e., a graph
of \(\rho(\hat{{z}}_k)\) versus \(\hat{{z}}_k\), \(k=1,\ldots,n\)), and under the presence of a right-censored sample, the function plot()
produces a graph
of the survival function of the error distribution.