This document discusses the four main types of measurement scales: nominal, ordinal, interval, and ratio.
Nominal scales assign numbers or symbols to qualitative categories for labeling purposes only, with no numerical significance or ordering. Ordinal scales arrange data in order but differences between ranks cannot be determined.
Interval scales have equidistant values where differences are meaningful, but have an arbitrary zero point. Ratio scales have a true zero point origin allowing multiplication and division, and include scales like height, weight, and money.