validity

• Types of validity

  • Validity = whether an observed effect is genuine and represents what is actually ‘out there’ in the real world
  • Data can be reliable but not valid
  • Internal validity = control within a study (eg reduce demand characteristics)
  • External validity = generalising to other settings, population or eras
  • Ecological validity = whether findings can be generalised from one setting to another (most particularly generalised to everyday life). eg realism of the participants tasks
  • Temporal validity = findings should be consistent over time (eg Asch‘s study may lack temporary validity as it was conducted during a conformist era in US history)
• ways of assessing validity

  • Face validity = a test looks like it measures what it claims to do
  • Basic measure to assess validity
  • Concurrent validity = whether findings are similar to those on a well established test (correlation should exceed +.80 for validity)
• improving validity in:

  • Experiments = control group (ensure changes in the DV were due to the IV) and standardisation and single-/double-blind (minimise impact of participant reactivity and investigator effects)
  • Questionnaires = lie scale (control effects of social desirability) and confidentiality
  • Observations = behavioural categories should be well-defined, operationalised, not ambiguous or overlapping
  • Qualitative research = triangulation (using multiple different sources as evidence) and interpretive validity (coherence of narrative and direct quotes from participants)