The benefits from a measurement program are not obtained until the measures/metrics are used.

Nominal Data

This data can be categorized. For example, a program can be classified as database software, operating system, etc. Nominal data cannot be subjected to arithmetic operations of any type, and the values cannot be ranked in any "natural order." The only possible operation is to determine whether something is the same type as something else. Nominal data can be objective or subjective, depending on the rules for classification.

Ordinal Data

This data can be ranked, but differences or ratios between values are not meaningful. For example, programmer experience level may be measured as low, medium, or high. For ordinal data to be used in an objective measurement the criteria for placement in the various categories must be well defined; otherwise, it is subjective.

Interval Data

This data can be ranked and can exhibit meaningful differences between values. Interval data has no absolute zero, and ratios of values are not necessarily meaningful. For example, a program with a complexity value of 6 is four units more complex than a program with a complexity of 2, but it