Levels of measurement

• Define nominal data

  Data that is grouped into discrete named categories (no overlap)

  
  

  Scores in a category are described as frequencies

  
  

  E.g. number of students from different ethnic backgrounds in school.
• Define ordinal data

  Data that is in the form of ranks, ratings or scores.

  
  

  E.g. rating of attractiveness of the opposite sex
• Define interval data

  Data that has fixed units of measurement but do not have a real zero value.

  
  

  E.g. Temperature or IQ scores