Optionaldirection"auto" (default): "<" when the median of the controls is at most the median of the cases, else ">"
(pROC's rule: the AUC can then be below 0.5). "<": the cases have the higher values; ">": the lower values.
OptionallevelsThe control and the case level of the response, in this order (numbers, strings or booleans, compared as R
compares them as strings). Default: the first two of the response's sorted levels (numbers in numerical order,
strings by code point, false before true). Not with the { controls, cases } form.
OptionalnaDrop the observations with a missing response or predictor (default true); false makes them an error.
Options for roc.