Assessing the psychometric properties of the Army STARRS' vertical unit cohesion scale: A large-scale, longitudinal study.

Unit cohesion is the extent to which military service members feel committed to and supported by their military unit or, conversely, feel overlooked, neglected, and/or alienated. Unit cohesion reflects an important aspect of military social support and can act as a protective factor against mental health challenges, particularly in challenging situations. Theoretical suppositions and emerging evidence suggest that different types of unit support, specifically, vertical unit cohesion and horizontal unit cohesion, uniquely matter for service member well-being. Vertical unit cohesion (support from leaders in the unit and other higher-ranking positions) may be of universal importance to service members with implications for career progression and personal wellbeing, while horizontal unit cohesion (support from fellow unit members and peers) may be of importance under certain circumstances. Informed by the psychometric theory of scale development and validation, the dimensionality of unit cohesion theory, and the need for brief, sound measurement tools, this study first examined the psychometric properties of the Army STARRS four-item Vertical Unit Cohesion Scale in a longitudinal analysis with a large, diverse sample of Soldiers from the Pre/Post Deployment Study component of the Army STARRS dataset (N = 10,116). Then, exploratory analyses were conducted to examine the properties of the Horizontal Unit Cohesion Scale and understand the relationship between vertical and horizontal unit cohesion. Strong evidence for the Vertical Unit Cohesion Scale's psychometric soundness was established regarding factor structure, measurement invariance overtime, and construct validity. Conversely, preliminary evidence suggests that the three-item measure of Horizontal Unit Cohesion should be used with caution. Implications for researchers and military leadership are provided.