issues and reliability of validity

• Reliability


  Consistency of an outcome or results of an investigation, which means same results is found again + again
• Reliability


  • If standardised procedure not used, can be variability in procedure, result in unreliable findings
• Reliability in sampling methods


  • If sampling method or technique leads to biased sample
  • Outcome of research may not be relied upon to occur again, as it could differ if study was replicated
• Reliability in experimental designs

  • In an independent measures design, participants differ between conditions, so there is variability between groups because of participant variables
  • Can lead to unreliable findings
• Validity


  Refers to extent to which a study measures what it intends to measure
• Internal validity


  • If a study is designed to measure aggression in preschool children, then it is important that measures of aggression actually test that characteristic
• External validity


  • Sample of preschool children must correctly represent intended target population
• Validity in sampling methods

  • If a sample error occurs findings of research are untrue of target population
  • This affects (external) validity of results
• Validity in experimental design

  • If a repeated measures design is used and order effects are shown, this can mean that outcome may be a result of practice or fatigue + not the intended variable being investigated
  • Demand characteristics are more likely in a repeated measures design, which can also invalidate results
• Qualitative methods


  • Emphasis is on gathering lots of detailed information from which ideas + theories emerge
  • Can include case studies, unstructured interviews + participant observation
  • These methods are exploratory
  • Not easy to replicate, may not produce reliable findings
  • Info gathered restricted to individuals being studied, limits generalisability (external validity)
  • Can have researcher bias and investigator effects, lower validity
  • Use triangulation to ensure they do not lose their objectivity
• Quantitative methods


  • Follow normal scientific route of enquiry, starting with a hypotheses to test a theory
  • Study is designed + conducted to test hypothesis + results are generated to support or not support theory
  • Are typical of experiments + some types of questionnaires + observations
  • Designed to gather facts + measure behaviour that can be applied to target population, which means that they reproduce data that is generalisable to others (external validity)
  • Allows researcher to remain detached from participants
  • Method is seen as more objective + less open to researcher bias