Levels of measurement

• Levels of measurement


  The numerical data at varying levels of precision that psychologists use to record data from participants
• Types of levels of measurement

  • Nominal
  • Ordinal
  • Interval
• Nominal data


  Data that refers to categories or the number of items in each category
• Ordinal data


  Data that can be placed in order, but the difference between each point is not necessarily the same
• Ordinal data


  • Position in a writing competition
  • Height among classroom students
  • Self-reported happiness
• Interval data


  Data that uses equal units of measurement, with no absolute zero point
• Interval data


  • Length in millimetres
  • Quantity of a drug in milligrams
  • Speed in miles per hour
  • Age in years
  • Temperature in degrees
• Ratio data


  Interval data with an absolute zero point
• For AQA level psychology, ratio data is treated as interval data
• Converting interval data to ordinal data

  1. List participants from highest to lowest score

  2. Assign rank positions, with tied scores sharing the same rank
• Converting ordinal data to nominal data

  1. Create separate categories

  2. Place highest ranked half in one category, lowest ranked half in the other