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Measurement Scales



From Wikipedia entry on Levels of Measurement:
The "levels of measurement", or scales of measure are expressions that typically refer to the theory of scale types developed by the psychologist Stanley Smith Stevens. Stevens proposed his theory in a 1946 Science article titled "On the theory of scales of measurement".[1] In that article, Stevens claimed that all measurement in science was conducted using four different types of scales that he called "nominal", "ordinal", "interval" and "ratio".






Summary Table


 

Nominal

  • Named categories. 
  • No order.
  • Example:  Ford, Chevy, Dodge

Ordinal

  • Ordered levels.
  • The distance between the levels lacks meaning.  A rating of "4" is not twice as much as a rating of "2".
  • Example:  Preference rated from 1 to 5

Interval

  • Ordered levels.
  • The distance between the levels has meaning.
  • A measure of zero does not indicate an absence of the quality that is being measured.
  • Example:  Degrees Fahrenheit

Ratio

  • Ordered levels.
  • The distance between the levels has meaning.
  • A measure of zero does indicate an absence of the quality that is being measured.
  • Example:  Degrees Kelvin

Resources

See StatSoft Electronic Textbook section on Measurement Scales
 
See Wikipedia entry on Level of Measurement

 



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