I know this question is stupid, but it is really make me confused. If we have the gender variable, and then encode it as 0 (female) and 1 (male). Most people would say we should treat gender as nominal data, since male and female are not quantitative values.
However, what if we consider the number of Y chromosome? In general, male has one Y chromosome, and female has zero Y chromosome. The number of Y chromosome is the ordinal variable. Then, we can get the data like this,
observation gender #Y chromosome 1 male (1) 1 2 female(0) 0 3 female (0) 0 4 male (1) 1
In that case, is it okay that we treat gender (0,1) as ordinal variable?