A specific subset of nominal level data is dichotomous data. Dichotomous data are nominal but have only two possible
categories. A common example is mortality. The values for mortality are either live or die. Other dichotomous variables
are things that can be measured as yes or no, on or off, or present or absent. Dichotomous variables possess characteristics
beyond those of other nominal level data, but such a discussion is beyond the scope of this article.