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Forms of Reliability


  • Reliability: Do indicators produce consistent results in measuring a concept?
  • Just as there are different forms of validity, there are different forms of reliability.
  • Are you seeking consistency over time, over observers, or across measures?
    • Test-retest reliability refers to consistency over time:
      • To what extent will a test at time t yield the same results at time t+1?
      • Your research determines whether you value this type of reliability.
    • Inter-observer reliability refers to consistency across researchers.
      • To what extent do different researchers produce identical scores on indicators?
      • This is especially important for research projects dependent on team research.
      • It's also important when one researcher uses a subjective method, such as content analysis.
    • Internal consistency applies in using multiple indicators in an "effects" model of measurement.
  • We will measure scale reliability only in the sense of internal consistency.