Learn in the textbookData Operations and Levels of Measurement
DefinitionAn ordinal scale (順序尺度) is a scale in which the order of values, larger or smaller, higher or lower, has meaning, but the intervals between values are not necessarily equal.
ExplanationSurvey ratings such as satisfied, somewhat satisfied and neutral, and finishing positions in a race, are examples. You can compare which comes first, but nothing says the gaps between neighboring levels are equal, so differences and averages are hard to interpret. The usual representative value is the one in the middle when the values are lined up in order, called the median (中央値).
AnalogyWith hotel star ratings, nobody guarantees that the step from three stars to four is as big as the step from one star to two.