Evaluating Loneliness Measurements across the European Union

Loneliness has been associated with several detrimental effects for individuals and societies, making it a priority for monitoring across the European Union. While many loneliness measures exist, notable gaps exist regarding knowledge of their psychometric structure, reliability, comparability, and validity, particularly as it pertains to their suitability for EU-wide population surveys. Relying on data from the EU Loneliness Survey covering the 27 EU member states (N=25,646), we examined the factor structure, internal consistency, measurement invariance, and construct validity of the six-item De Jong Gierveld Loneliness Scale (DJGLS-6), the three-item UCLA Loneliness Scale (T-ILS), and a single-item measure of loneliness. Our analyses followed a two-step process, with exploratory analyses conducted in an exploratory fold, followed by pre-registered confirmatory analyses in a confirmatory fold. The DJGLS-6 showed mixed psychometric performance across countries, with adequate internal consistency, limited cross-country invariance, and generally sufficient construct validity. The T-ILS showed more robust performance, with good internal consistency, scalar invariance across all countries, and sufficient construct validity in most countries. The single-item measure showed acceptable construct validity in a smaller subset of countries. Overall, these findings suggest that the T-ILS may currently be the most suitable measure for monitoring loneliness across the European Union. In addition, discrepancies between content-based categorizations of loneliness measures and empirical performance reveal limitations in current construct validation practices and a lack of consensus about key external correlates and their expected strength. Addressing these gaps will require more explicit theoretical models and clearer predictions linking loneliness measures to their nomological networks.