What Are You Ruminating About? The Development and Validation of a Content-Dependent Measure of Rumination
Abstract
Rumination is a past-focused distress response characterized by repetitive and passive fixation on symptoms, possible causes, and/or consequences of distress (Nolen-Hoeksema, 1991). To date, previous measures of rumination have focused on general levels of rumination without considering the content of ruminative thought. This dissertation describes the development of a new rumination measure, the Rumination Domains Questionnaire (RDQ), which considers the content of ruminative thought. Furthermore, the present dissertation describes group differences found in the content of ruminative thought that have been difficult and/or unfeasible to capture in research prior to the introduction of the RDQ. In the introduction, a case is made for how scientists and practitioners may benefit from such a scale and how such a scale should be developed based on the scale development literature. Study 1 describes the rigorous procedures which constituted scale development, including item generation and selection based on empirical criteria. Study 2 is concerned with the validation of the RDQ in terms of reliability, concurrent validity, convergent validity, discriminant validity, and structural validity using two samples: a student sample and a community sample. In this study, reliability, concurrent, convergent, and to a lesser extent discriminant validity is supported, as was the scale’s structural validity as a 10-factor scale (domains as factors). In Study 3, the criterion and incremental validity of the scale was tested using daily diary methods. In this study, daily rumination (specific to a domain) was predicted by the corresponding RDQ domain score, whereas the RDQ-total score predicted relevant outcomes such as negative mood and amotivation, often even above and beyond the effect of other rumination scales. In Study 4, criterion validity was assessed once again, reliability was demonstrated (both internal consistency and test-retest reliability), and relationships with social desirability were examined. Moreover, two samples were collected: a student sample and an older sample, with which sex differences and differences between the samples in rumination content, as well as anxiety and depression, were investigated. Overall, these studies provide promising preliminary evidence for the RDQ’s validity, which may be used to assess the previously oft-neglected area of rumination content.