Validity

Validity

1. Internal validity

   • Participant effects: Participant's behaviour is influenced by the attention of the researcher
   • Demand characteristics: Participants behave differently as a consequence of cues in the environment
   • Experimenter bias: the effect that the experimenters expectation has on the participants behavioour
   • Investigator effects
     • Investigator experimental design effect
     • Investigator loose procedure effect
     • Investigator fudging effect
     • Experimenter personal attributes effect
   • Situational variables
     • Environmental variables e.g. time of day
     • Order effects e.g. the practice effect
     • Investigator effects (see above)
     • Demand characteristics
   • Participant variables
     • Characteristics e.g. age, intelligence
     • Gender due to the way we are socialised
     • Participant effects e.g. demand characteristcis
   • Changes in the experimental group may be due to reasons other than the IV

2. External validity

   • Ecological validity: Generalisability to different settings
     • Mundane realism: how much research mirrors the real world
     • Generalisability: how much the findings from one study can be generalised to other settings
   • Population validity: Generalisability to different populations
   • Historical validity: Generalisability to different times
   • Enhanced by replications

3. Self resports

   • Social desirability bias: Participants give false answers to present themselves in the best way
     • Lie scale: questions where the true answer makes the participant look bad, high proportions of lie means other answers are likely to lack validity
   • Interviewer bias: The interviewers behaviour biases the answer given
   • Leading questions: Don't represent the participants true feelings
   • Content validity: If the report is measuring what it intends to
     • Face validity: whether the measure looks like its measuring what it intends to
   • Concurrent validity: Whether two tests on the same topic produce similar results
   • Predictive validity: Whether facts predicted by the report are true e.g. IQ and grades
   • Construct validity: assessed by looking at the underlying theory in questions

4. Observations

   • Internal validity
     • Observations are made valid by using behavioural categories
     • Observer bias: When an observers results are influenced by their expectations
       • Reduced by using more than one observer
   • External validity
     • Greater ecological validity as they have more natural behaviour
       • Conduct in varied settings
     • May have low population validity
       • Use varied populations