data("TravelMode")mode.
1 to 200."car", "air", "train", or "bus"."no" and "yes".In MRSP-terminology, variables wait, vcost, travel and gcost are
category-specific since they take different values for different categories of mode. The variables
income and size are global. In the literature on discrete choice modelling,
these two variable types are called alternative-specific and individual-specific, respectively.