Validity The concerns of reliability and validity can ... be seen as leading to two complementary objectives in designing and developing tests: (1) to minimize the effects of measurement error, and (2) to maximize the effects of the language abilities we want to measure. (Bachman, 1990:161)
While test reliability is concerned with minimising the effects of measurement error, test 6 validity involves ensuring that a test truly tests the abilities which we are looking to assess. Owen (2001: 20) describes validity as the “sine qua non of language testing” and laments the lack of consensus and the “dispiriting” number of aspects of validity mentioned in the standard literature. There is clearly a great degree of overlap among the various aspects (Owen, 2001: 22), and both Bachman (1990:238) and O‟Sullivan (2006: 96) support Messick‟s view of validity as a “unitary though multifaceted concept” (Bachman, 1990: 238). Here is a brief overview of the most commonly highlighted aspects