what is a polr function used for? what is the plot in polr what is an example of a logistic regression? what is polr what is the y axis of tau what is the axis of residual deviance what are the axes of the polr function polr how does it work what is the polr function in r what is the plot for plot of residual deviance why do you use polr function what type of graph is polr what is plot(pr) of a r model what is polr plot what is the axis of residual deviance in r how to use polr function what is polr what is polr in r used for how to understand a plot used for a linear regression what is a polr pair example