Reliability

• reliability = consistancy
• reliable but not valid = if a measurement is not reliable then it can’t be valid
• valid but not reliable = test/ assessment not valid its not reliable

  (1 possibility = in the questionnaire, research has a choice between open/closed questions)
• internal validity = a measure of whether a questionnaire is consistent within itself
• type of internal reliability:

  • split half method = test items are split into two halves and the scores on both halves compared, scores should be similar is the test is reliable.
• external reliability = a measure of whether something varies from one time to another (i.e is consistent over time)
• type of external reliability:

  • test retest = the same psychological test is given to the same p’s on 2 occasions to see if the same result occurred.