Enhancing the Assessment of Gratitude in Mindfulness Research: a Rasch Analysis of the 6-Item Gratitude Questionnaire

Abstract

Abstract Objectives The 6-item gratitude questionnaire (GQ-6) is a widely used measure reported to be reliable and valid under traditional and Rasch investigations. However, recent investigations were inconsistent regarding the item structure of the GQ-6, with three investigations concluding that item 6 be removed. Previous Rasch analyses also did not produce interval conversion tables, a key benefit of this method which provides a means of improving scale accuracy and aligning the scale with the fundamental principles of measurement. Methods A Partial Credit Rasch Model was used to evaluate psychometric properties of the GQ-6 using a combined sample of 663 respondents from the USA (n = 345) and India (n = 318). Results Initial analysis showed significant scale dysfunction, with overall and individual item misfit, local dependency, disordered response thresholds, instances of differential item functioning by age and nationality, along with poor reliability. Through the use of recent advances in the Rasch methodology, locally dependent items were combined into two super-items and the best fit to the Rasch model was obtained with evidence of strict unidimensionality, invariance, and strong reliability. Results indicate the GQ-6 is suitable for individual and group assessment, while also permitting the creation of an ordinal-to-interval conversion algorithm which has been provided here. Conclusions This study confirmed the robust psychometric properties of the GQ-6 after minor modifications and provides a means for clinicians and researchers to improve the accuracy of this widely used measure in mindfulness research and other relevant studies without modification of its original response format.