reliability

• what is reliability

  refers to how consistent the findings from an investigation or measuring device are. a measuring device is said to be reliable if it produces consistent results every time it is used
• what are the two ways of assessing reliability

  • test - retest
  • inter - observer reliability
• what is eternal reliability

  when a questionnaire or psychological test produces the same results every time it is used
• what is internal reliability


  when items in a questionnaire or psychological test are consistent within themselves
• test - retest

  assesses external reliability, by checking whether whatever is being studied has remained consistent over time
• inter - observer reliability

  assesses the consistency of observations, this is the degree to which different observers give consistent recordings of the same observation.

  this also applies for both inter - rater reliability and inter - interviewer reliability
• how to improve reliability for questionnaires

  measure reliability via the test - retest method. when comparing the two data sets they should produce a correlation which exceeds + 0.80.

  if the test produces a low correlation, then some aspects of the questionnaire would have to be rewritten or removed
• how to improve experiments

  lab studies are described as being reliable due to the high level of control and standardised procedures. this means that there is more chances for replication
• how to improve observations

  reliability of observations can be improved by making sure that behavioural categories have been operationalised, and that they are measurable and clear. behavioural categories should overlap, and all possible behaviours should be listed. then use inter - observer reliability