Stanley Smith Stevens

“The type of scale is defined by the group of transformations that leaves the scale form invariant.”

“The business of a scale of measurement is to state the conditions under which an equality is to be determined.”

“For seven years I have been hearing my colleagues say that one cannot measure sensation. I have been telling them that they are wrong.”

“Measurement is the assignment of numerals to objects or events according to rules.”

“In its most general form the power law states that equal stimulus ratios produce equal subjective ratios.”

“A rule is a convention, and the rules of measurement are man-made conventions.”

“The prothetic continua are those on which discrimination is a matter of 'how much'; the metathetic continua are those on which discrimination is a matter of 'what kind' or 'where'.”

“Any rule is arbitrary. The important thing is that the rule be stated.”