Development and validation of the interpersonal stress scale: An Item Response Theory Analysis

Background: Interpersonal stress is associated with significant declines in physical health and is a significant predictor of risk for the onset of some mental disorders. In spite of this, little is known about the assessment of this construct. This study aimed to apply Item Response Theory (IRT) to develop and examine psychometric properties of the Interpersonal Stress Scale (ISS) to assess five domains of interpersonal stress. Methods: Exploratory factor analysis and IRT were utilized to test validity and reliability of ISS. The study was conducted on 512 participants aged 15-45 years (M = 29.14; SD = 8.08) who were selected using convenience sampling method. Results: Current results showed a five-factor structure of the ISS and revealed that 32 items of the ISS could be scored using IRT methods. The ISS also showed satisfactory test-retest reliability (r = .83; p< .01) and internal consistency, with Cronbach's alpha coefficients ranging from .67 to .89. Moreover, the ISS scores were correlated with other constructs, which provides evidence for the predictive and divergent validity of the scale. Conclusions: These findings supported the Interpersonal Stress Scale as a reliable and valid tool to measure interpersonal stress in Iranian population.