Scale

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Ordered set of values, continuous or discrete, or a set of categories to which the attribute is mapped. [ ISO/IEC 99, ISO/IEC 15939, ISO/IEC 25000 ]

Other Definitions

Scale [ ISO/IEC/IEEE 24765
A set of values with defined properties.

Notes

  • The type of scale depends on the nature of the relationship between values on the scale. Four types of scales are commonly defined:
Nominal 
The measurement values are categorical. For example, the classification of defects by their type does not imply order among the categories.
Ordinal 
The measurement values are rankings. For example, the assignment of defects to a severity level is a ranking.
Interval 
The measurement values have equal distances corresponding to equal quantities of the attribute. For example, cyclomatic complexity has the minimum value of one, but each increment represents an additional path. The value of zero is not possible.
Ratio 
The measurement values have equal distances corresponding to equal quantities of the attribute where the value of zero corresponds to none of the attribute. For example, the size of a software component in terms of LOC is a ratio scale because the value of zero corresponds to no lines of code and each additional increments represents equal amounts of code.
These are just examples of the types of scales. Roberts[1] defines more types of scales. [ ISO/IEC 15939 ]
  • The type of scale depends on the nature of the relationship between values on the scale. Metrics using nominal or ordinal scales produce qualitative data, and metrics using interval and ratio scales produce quantitative data. [ ISO/IEC/IEEE 24765 ]

Example

  • A nominal scale which corresponds to a set of categories; an ordinal scale which corresponds to an ordered set of scale points; an interval scale which corresponds to an ordered scale with equidistant scale points; and a ratio scale which not only has equidistant scale point but also possess an absolute zero. [ ISO/IEC/IEEE 24765 ]

See also

Standards:

References

  1. F. Roberts. Measurement Theory with Applications to Decision Making, Utility, and the Social Sciences. Addison-Wesley, 1979
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