Validity

• Validity

  The extent to which an observed effect is genuine.

  Does it measure what it was supposed to measure? (Internal validity)

  Can it be generalised beyond the research setting within which it was found? (External validity)
• Internal validity

  • Refers to whether the effects observed in an experiment are due to the manipulation of the IV and not another factor.
  • Mainly affected by Demand characteristics, as people may act in a way they think is expected.
• External validity

  Relates to more factors outside of the investigation, such as generalising to other settings and other populations.
• Ecological validity

  • The extent to which findings from a research study can be generalised to other settings and situations.
  • Form of external validity.
  • E.g if the task that is used to measure the DV is not like real life (lacks mundane realism) this has lower ecological validity.
  • E.g word lists.
• Temporal validity

  • The extent to which findings from a research study can be generalised to other historical times and eras.
  • E.g high rates of conformity in Asch’s study were a product of a particularly conformity era.
• Face validity

  • Whether a test, scale, measure appears ‘on the face of it’ to measure what it is supposed to measure.
• Concurrent validity

  • The extent to which a psychological measure relates to an existing measure.
  • Close agreement between 2 sets of data would indicate tat new test has high concurrent validity.
  • Indicated by correlation between 2 data sets.
  • +80
• Improving validity in experiments

  • Using a control groups: Means that the researcher is better able to assess whether changes in DV were due to effect of IV.
  • Standardised procedures to minimise impact of participant reactivity and investigator effects.
  • Use of single blind and double blind procedures.
• Single blind

  Participants not aware of the aim. So reduces demand characteristics.
• Double blind

  Third party conducts investigations without knowing the aim.

  Reduces demand characteristics and investigator effects.
• Improving validity of questionnaires

  • Many questionnaires may incorporate a lie scale, to assess the consistency of a respondents response and control the effects of social desirability bias.
  • Validity may be further enhanced by assuring respondents that all data is kept anonymous.
• Improving validity of observations

  • Produce findings with high ecological validity as there is minimal intervention by researcher.
  • Especially covert observations so behaviour is more likely to be natural and authentic.
  • If behavioural categories are too broad this decreases validity.
• Improving validity of qualitative research

  • Higher ecological validity than quantitative data, as it has more depth and detail.
  • Used in case studies and interviews and is better able to reflect participants reality.
  • However researcher may still demonstrate interpretive validity of their conclusions.
• Interpretive validity

  The extents to which the researchers interpretations match the participants.
• Triangulation

  • Further enhances validity.
  • The use of different sources as evidence.
  • E.g using data from interviews and observations.