11.8 Validity

In course material, Woodley and Aczel (2011) urge readers to distinguish between validity and reliability.

Reliability is about whether the research can consistently obtain the same results using different methods.

Validity is about whether the methods being used are actually giving the researchers what  they claim such methods do. Campbell & Stanley (1963) stress that validity is the degree to which a study supports its conclusions.  The same authors subdivide validity in a number of ways, of which ‘external validity’, ‘internal validity’ and ‘construct validity’ (see Capaill, 2011).

Trochim (2007) concludes that the ‘theory of validity, and the many lists of specific threats, provide a useful scheme for assessing the quality of research conclusions.’


Campbell, D.T. and Stanley, J. (1963) ‘Experimental and quasi-experimental designs for research on teaching’, in Gage, N. (ed.) Handbook of Research on Teaching, Chicago, IL, Rand McNally, pp. 171–246.

Capaill, C. (2011) Validity available from http://cluasacapaill.wordpress.com/2011/04/23/validity/ (accessed 30 April 2011).

Woodley and Aczel (2011) Categorising research methods, available from http://learn.open.ac.uk/mod/resourcepage/view.php?id=409226&direct=1 (accessed 25 April 2011).

Trochim (2007) Introduction to Validity available from http://www.socialresearchmethods.net/kb/introval.php (accessed 29 April 2011).


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