To understand Akerlof's insight, suppose that the quality of used cars lies on a 0 to 1 scale and that the population of used cars is uniformly distributed on the interval from 0 to 1.

Interval - an interval scale is a scale of measurement in which the distance between any two adjacent units of measurement (also known as intervals) is the same, but the zero point is arbitrary.

The values on an interval scale can be added and subtracted, but can not be meaningfully multiplied or divided.