Validity

• Types of validity:

  1. Internal validity - face validity, concurrent validity
  2. External validity - population validity, ecological validity, temporal validity
• Internal validity - Inside the study

  • Is the research measuring what it intends to measure?
• Internal validity if affected by extraneous variables e.g. demand characteristics, researcher bias, e.t.c.
• External validity - outside the study

  • Whether the findings can be generalised outside the study
• Ecological validity - A form of external validity. The extent to which findings can be generalised beyond the setting of the study to other real life settings
• Population validity - A form of external validity. The extent to which findings can be generalised beyond the sample studied to the target population
• Temporal validity - A form of external validity. The extent to which findings remain true over time and can be generalised to other time periods
• Lab - High internal validity, lacks ecological validity
• Field - Low internal validity, high ecological validity
• Natural - Low internal validity, high ecological validity
• Quasi - Depends on the scenario/environment
• Face validity can be used to assess the validity of experiments
• How to conduct face validity:

  1. An independent psychologist in the same field looks at the experiment conditions
  2. See if the conditions look like they measure what they intend to measure (AO2) at first sight/face value
  3. If the researcher says 'yes' then the research is said to have face validity
• Concurrent validity can also be used to assess validity of experiments
• How to conduct concurrent validity:

  1. Compare the results of the new test (AO2) with the results from another similar test which has already been established for its validity using a stats test
  2. If results from both tests (AO2) are similar then we can assume the test is valid
  3. The correlation of the two results gained from an appropriate stats test should exceed +0.8 to be considered valid
• To improve validity in experimental research:

  • Use of a control group to assess that the IV has affected the DV (establishes cause and effect)
  • Standardised procedures/instructions to reduce investigator effects
  • The use of a single blind procedure to reduce demand characteristics
  • The use of a double blind procedure to reduce demand characteristics and investigator effects
  • Questionnaires/interviews - add in distractor questions