validity

• internal validity is the extent to which changes in a DV are legitimately caused by a change in an IV
• internal validity issues:

  • demand characteristics
  • researcher bias
  • social desirability
  • test is inaccurate
• to deal with demand characteristics, use a single blind study
• the deal with researcher bias, use a double blind study
• the deal with social desirability, ensure confidentiality
• the deal with the test being inaccurate, do a pilot study
• external validity= the extent which the findings can be generalised
• external validity issues:

  • ecological validity
  • population validity
• the deal with ecological validity, design the study to be carried out in real life settings
• the deal with population validity, carry out the study on different groups of people
• how to assess validity:

  • content validity
  • concurrent validity
  • construct validity
  • face validity
  • predicitve
• content validity= use an independent expert to assess the study
• concurrent validity= compare test in study to one that is already valid- same ppts do both test
• construct validity= use a theory to see if its valid
• face validity= researcher sees if test is measuring what it claims to measure
• predictive= researcher makes outcome predictions then compares then to the actual findings