It has properties of the ordinal level of measurement and
the differences in the values of the variable have meaning. A value of zero in
the interval level of measurement does not mean the absence of the quantity.
Arithmetic operations such as addition and subtraction can be performed on
values of the variable is called interval.
While nominal the values of the variables name, label or categorize. In
addition, the naming scheme does not allow values of the variables to be
arranged in a ranked or specific, order.
The observable traits expressed by an organism are referred to as its phenotype. An organism's underlying genetic makeup, consisting of both physically visible and non-expressed alleles, is called its genotype.
