Loneliness is an unpleasant state arising from the gap between an individual's desired and actual social relationships. Prevalent across cultures and ages, this phenomenon is linked to mental health issues (depression, anxiety) and physical ailments (chronic diseases). As a subjective experience, loneliness is typically measured using self-report tools. The DiTommaso scale views loneliness as multidimensional (social and emotional), but in Iran, its validation using modern psychometric methods like Item Response Theory (IRT) and network analysis has not been conducted. Unlike classical test theory, these methods provide more precise insights into item performance and construct structure. IRT models the relationship between latent traits and responses, while network analysis visualizes item relationships, identifying key items.

The main objective of this study is to examine the psychometric properties of the DiTommaso Social and Emotional Loneliness Scale using IRT and network analysis.

Given the rising prevalence of loneliness and its adverse effects, improving measurement tools with advanced methods is crucial. This research, by providing more accurate data, aids in designing effective interventions and enhancing individuals' quality of life.

Methodology: This cross-sectional psychometric study collects data via an online questionnaire from at least 350 students aged 18–35 at Tehran universities. Sampling is convenience-based and voluntary. The tool is the short version of the DiTommaso scale (14 items, 5-point Likert), with established validity and reliability. Data analysis employs IRT and network analysis.

Ethical considerations include obtaining ethics approval, informed consent, and ensuring data confidentiality.