scale, ordinal

n. A quantitative scale with magnitude, but lacking equal intervals or an absolute zero, used primarily to rank or rate individuals or objects. Ordinal scales provide information about degrees of difference but do not provide any information about the meaning or amount of difference between rankings or ratings. The lack of equal intervals prevents the direct comparison of the difference measurement between any two points. For example, when runners complete a race, an ordinal scale is used to rank first, second, third, and fourth place, and so on, but the ranking does not tell you the difference between first and second place; nor can you assume that the first-place runner was four times as fast as the fourth-place runner. The ordinal rankings simply provide a measure of the degree of difference between runners. Because of the lack of equal intervals, the most appropriate calculations for ordinal scale data are mode, median, range, and percentile rank. – BJM