The Investment Model Scale: Measuring commitment level, satisfaction level, quality of alternatives, and investment size

TLDR

The Investment Model Scale was created to measure commitment level, satisfaction, quality of alternatives, and investment size in relationships. The study aims to establish a reliable and valid scale to facilitate future research on commitment and interdependence in close relationships. The authors assessed internal consistency and factor structure of the scale and examined its associations with relationship quality and personal disposition measures across three studies. The scale demonstrated good internal consistency, a clear four‑factor structure, moderate correlations with relationship functioning, no link to personal dispositions, and predictive validity for later dyadic adjustment and relationship status.

Abstract

Abstract Three studies evaluated the reliability and validity of the Investment Model Scale, an instrument designed to measure four constructs, including commitment level and three bases of dependence–satisfaction level, quality of alternatives, and investment size. In all three studies, reliability analyses revealed good internal consistency among items designed to measure each construct. Also, principal components analyses performed on scale items revealed evidence of four factors, with items designed to measure each construct loading on independent factors. Studies 2 and 3 examined associations of model variables with instruments measuring diverse qualities of relationships and assorted personal dispositions. As anticipated, Investment Model variables were moderately associated with other measures reflecting superior couple functioning (e.g., dyadic adjustment, trust level, inclusion of other in the self), and were essentially unrelated to measures assessing personal dispositions (e.g., need for cognition, self‐esteem). In addition, Study 3 demonstrated that earlier measures of Investment Model variables predicted later levels of dyadic adjustment and later relationship status (persisted vs. ended). It is hoped that the existence of a reliable and valid Investment Model Scale will promote further research regarding commitment and interdependence in ongoing close relationships.