Psychometric characteristics of the Mobility Inventory in a longitudinal study of anxiety disorders: replicating and exploring a three component solution.

Psychometric characteristics of the Mobility Inventory (MI) were examined in 216 outpatients diagnosed with panic disorder with agoraphobia participating in a longitudinal study of anxiety disorders. An exploratory principal components analysis replicated a three-component solution for the MI reported in prior studies, with components corresponding to avoidance of public spaces, avoidance of enclosed spaces, and avoidance of open spaces. Correlational analyses suggested that the components tap unique but related areas of avoidance that were remarkably stable across periods of 1, 3, and 5 years between administrations. Implications of these results for future studies of agoraphobia are discussed.