Loneliness is increasingly a focus of governments and health systems due to its potential adverse effects. Various ways to measure it have been developed but the psychometric properties of common instruments have not yet been evaluated across all countries in the European Union (EU).

 

In this study, Paris et al. (2025) will examine three measures of loneliness across 27 EU member countries. An online survey (n = 25,646) incorporated three instruments which were translated into national languages: the De Jong Gierveld Loneliness Scale (6 items), the three-item UCLA Loneliness Scale (3 items), and a single-item measure (“How much of the time, during the past 4 weeks, have you been feeling lonely”). The factor structure, internal consistency, and measurement invariance for the 6- and 3-item measures will be assessed, as well as the construct validity of all three measures using nomological networks. The authors have adopted an n-fold procedure to analyse the data, with a first exploratory fold using half of the data to establish hypotheses for each question and a second confirmatory fold using the remainder of the data to test the hypotheses. The results of the study will provide important information about the psychometric properties of commonly used loneliness instruments, and can indicate which measures are appropriate for loneliness monitoring across the EU.

 

The study plan was refined across four rounds of in-depth review with input from four reviewers, Thuy-vy Nguyen, Joe Bathelt, Mary Louise Pomeroy, and Drew Altschul, and the recommenders, after which it was judged to meet the Stage 1 criteria and received in-principle acceptance.
 
URL to the preregistered Stage 1 protocol: https://osf.io/2s38v

 
Level of bias control achieved: Level 3. At least some data/evidence that will be used to the answer the research question has been previously accessed by the authors (e.g. downloaded or otherwise received), but the authors certify that they have not yet observed ANY part of the data/evidence
 
List of eligible PCI RR-friendly journals:
 

 

 

Paris, B., Ropovik, I., Silan, M., d'Hombres, B., Casabianca, E., & IJzerman, H. (2025). Evaluating Loneliness Measurements across the European Union. In principle acceptance of Version 4 by Peer Community in Reigstered Reports. https://osf.io/2s38v