Categorical variables are non-numeric "category" variables, e.g. color. Ordered categorical variables are category variables that have a quantitative dimension that can be ordered but is not on a regular scale. Doctors rate pain on a scale of 1 to 10 - a "2" has no particular numeric content, nor does a "3," but we can say that 3 represents more pain than 2 (but probably not 50% more, nor, necessarily, the same increment that moving from 9 to 10 represents). Ordered categorical variables can often be successfully used in statistical modeling, even though they may not meet the strict requirements associated with a particular method.