Application of the Rasch model to measure five dimensions of wellness in community-dwelling older adults.

BACKGROUND AND PURPOSE: Nurse researchers and practicing nurses need reliable and valid instruments to measure key clinical concepts. The purpose of this research was to develop an innovative method to measure dimensions of wellness among older adults. METHOD: A sample of 5,604 community-dwelling older adults was drawn from members of the COLLAGE consortium. The Wellness Assessment Tool (WEL) of the COLLAGE assessment system provided the data used to create the scores. Application of the Rasch analysis and Masters' partial credit method resulted in logit values for each item within the five dimensions of wellness as well as logit values for each person in the sample. RESULTS: The items fit the Rasch model, and the composite scores for each dimension demonstrated high reliability (1.00). The person reliability was low: social (.19), intellectual (.33), physical (.29), emotional (.20), and spiritual (.29). The small number of items within each dimension and the homogenous sample appear to have contributed to this low reliability. CONCLUSION: Ongoing research using multidimensional tools to measure dimensions of wellness among older adults is needed to advance wellness science and wellness promotion in nursing practice.