Decision values can be measured with a nominal (qualitative) or logical (quantitative) scale. Nominal measurement consists of identifying different options for the outcome of a variable without implying any logical ordering. Logical scales can be ordinal (simply ordered) or cardinal, where cardinal is further categorized as either interval or ratio.

With ordinal scales, the intervals between the values are not necessarily equal, e.g., Grade A, Grade B or Grade C for some material. If an ordinal scale has a zero point, it is usually arbitrary and has no meaning associated with zero.

On interval measurement scales, one unit on the scale represents the same magnitude on the trait or characteristic being measured across the whole range of the scale. A ratio scale is also an interval scale but it has a true zero (e.g., Kelvin temperature as opposed to Fahrenheit). With a ratio scale you can say 100 is twice as much as 50.