How can Item-response Theories Improve Questionnaire Research in Health Psychology?
C. Gibbons1
1University of Manchester, NIHR Collaboration for Applied Health Research and Care, UK
Questionnaire-based research is ubiquitous in Health Psychology. However a large number of widely-used questionnaire measures were developed and validated using ‘classical’ techniques that, when used alone, are not sufficiently sensitive to uncover important measurement issues; which may lead to inaccuracies and biases in the results of studies that rely on these measures. Modern psychometric techniques including item-response theory (IRT) can ensure that questionnaires are capable of ‘fundamental measurement’ potentially increasing the accuracy and reliability of Health Psychology research. This talk will briefly introduce item-response theories, including the Rasch model, and describe how these methods may be used alongside classical techniques to improve the quality of questionnaire measures in Health Psychology. The talk will give illustrative examples of the successful application of item-response theories to develop and validate a number of questionnaires including the Hospital Anxiety and Depression Scale (HADS), the Patient Health Questionnaire-9 (PHQ-9), the Multimorbidity Illness Perceptions Scale (MULTIPleS) and the Relationship Styles Questionnaire (RSQ).