Ordinal scales of measurement have the property of both classifying and magnitude. Subjects are categorized into different rank ordered groups. Each value on the ordinal scale has a unique meaning, and it has an ordered relationship to every other value on the scale. From the table,  we can conclude that the customer prefers historical fiction to science fiction, science fiction to detective fiction, detective fiction to romance. However, even though the differences in the consecutive numbers of the ranks are equal, we cannot say that how much the customer prefers one type of book over another type. That is, consecutive categories do not represent equal differences of the measured attribute.