Study notes


  • Levels: AS, A Level
  • Exam boards: AQA, Edexcel, OCR, IB

Validity refers to whether a measure actually measures what it claims to be measuring. Some key types of validity are explored below.

Face validity

Face validity is a measure of whether it looks subjectively promising that a tool measures what it's supposed to

  • e.g. It might be observed that people with higher scores in exams are getting higher scores on a IQ questionnaire; you cannot be sure that these are directly linked, but on the surface it appears that exam scores are a reasonable indication of IQ scores, so your measure shows good face validity.

Internal validity

Internal validity is a measure of whether results obtained are solely affected by changes in the variable being manipulated (i.e. by the independent variable) in a cause-and-effect relationship. Two key types of internal validity are:

  • Construct validity – asks whether a measure successfully measures the concept it is supposed to (e.g. does a questionnaire measure IQ, or something related but crucially different?).
  • Concurrent validity – asks whether a measure is in agreement with pre-existing measures that are validated to test for the same [or a very similar] concept (gauged by correlating measures against each other).

Internal validity can be assessed based on whether extraneous (i.e. unwanted) variables that could also affect results are successfully controlled or eliminated; the greater the control of such variables, the greater the confidence that a cause and effect relevant to the construct being investigated can be found.

External Validity

External validity is a measure of whether data can be generalised to other situations outside of the research environment they were originally gathered in. Two key types of external validity are:

  • Temporal validity – this is high when research findings successfully apply across time (certain variables in the past may no longer be relevant now or in the future).
    • e.g. Changes in attitude towards gender roles over time could lower the temporal validity of data from past experiments when applied to modern day research.
  • Ecological validity – whether data is generalisable to the real world, based on the conditions research is conducted under and procedures involved.
    • e.g. Laboratory research can exert a high degree of control over extraneous variables that would otherwise vary in a natural environment, so results might be considered too ‘artificial’ and thus possess low ecological validity.
      • However, mice, for example, might behave in the same way in a laboratory and in the wild, so laboratory experiments could arguably still maintain high ecological validity here.

The external validity of an experiment can be assessed and improved by replicating a study at different times and places, and obtaining similar results. For example, confidence in the generalisability [and in turn external validity] of results is increased when research is successfully replicated across different cultures.


Advertise your vacancies with tutor2u

Much cheaper & more effective than TES or the Guardian. Reach the audience you really want to apply for your teaching vacancy by posting directly to our website and related social media audiences.

Find our more ›

Advertise your teaching jobs with tutor2u