validity

→is the extent to which a test measures what it claims to measure

  • we use the definition above to define internal validity


having consistency (reliability) is important but that alone isn’t enough. a measure might give the same result everytime, but if it isn’t measuring the right thing, results are meaningless

this is why we use validity

main question is: are you measuring what you intend to measure? and, are there extraneous variables that aren’t controlled


external validity→ whether the findings can be generalised beyond the research setting to other people, situations, or times


what impacts internal validity?

  • researcher effects

  • participant variables

  • poor controls in places

  • social desireability

what impacts external validity?

  • biased sample

  • very artificial conditions


2 methods for assessing validity:

face validity→ whether a test looks like its measuring what its intention is

concurrent validity→ comparing current test to previously validated test


how to improve validity in an experiment:

  • use a control group (check if DV is affected by IV)

  • standardise procedures to reduce differences

  • use blind procedures to reduce researcher effects + reduces demand charcteristics

and questionnaires?

  • include a lie scale to indentify inconsistency or socially desireable responses (asking the same questions in different ways)

  • reassure participants their answer is confidential

and observations?

  • state clear behavioural categories


definitions of those affeciting internal validity:

→confounding variables: an unwanted variable changes alongside the IV, meaning we cannot be certain the IV caused the results

→poor operationalisation: variables aren't clearly defined or measured, meaning the study may not be measuring what it intends to measure

→confirmation bias: is the tendency to search for, interpret and remember information that supports our existing beliefs, while ignoring information that contradicts them


types of external validity

→ecological validity: whether findings can be generalised to real-life settings

→population validity: whether findings can be generalised to other people or populations

→temporal validity: whether findings can be generalised to different time periods