Applying methods to evaluate construct validity in the context of A level assessment

Validity is a central principle of assessment relating to the appropriateness of the uses and interpretations of test results. Usually, one of the inferences that we wish to make is that the score reflects the extent of a student’s learning in a given domain. Thus, it is important to establish that the assessment tasks elicit performances that reflect the intended constructs. This research explored the use of three methods for evaluating whether there are threats to validity in relation to the constructs elicited in international A level geography examinations: (a) Rasch analysis; (b) analysis of processes expected and apparent when students answer questions; and (c) qualitative analysis of responses to items identified as potentially problematic. The results provided strong evidence to support validity with regard to the elicitation of constructs although one question part was identified as a threat to validity. Strengths and weaknesses of the methods can be identified.