A Summary of Measurement Scales, Their Characteristics, and Their Statistical Implications
Nominal
A scale in which the numbers serve as labels rather than have numeric value (e.g., gender where 1=male; 2=female; 3=nonbinary). Can be used for determining the mode, the percentage values, or the chi square.
Ordinal Scale
A scale that “measures” in terms of such values as “more” or “less,” “larger” or “smaller,” but without specifying the size of the intervals (e.g., 78%iles or fifth place). Can be used for determining the mode, percentage, chi square, median, percentile rank, or rank correlation.
Interval Scale
A scale that measures in terms of equal intervals or degrees of difference, but whose zero point, or point of beginning is arbitrarily established (e.g., 32 degree Fahrenheit). Can be used for determining the mode, the mean, the standard deviation, the t test, the F test, and the product moment correlation.
Ratio Scale
A scale that measures in terms of equal intervals and has an absolute zero point of origin (e.g., 72 inches tall). Can be used for determining the geometric mean, the harmonic mean, the percent variation and all other statistical determinations.
The scale is not the number. It is the label attached to the number (e.g., inches, gender, etc.)
Del Siegle, Ph.D.
University of Connecticut
Neag School of Education – University of Connecticut
del.siegle@uconn.edu
www.delsiegle.info