Psychometric analysis of the three item loneliness scale in the Czech Republic

(2025) 13:21 Meier et al. BMC Psychology https://doi.org/10.1186/s40359-024-02204-8 BMC Psychology Open Access RESEARCH Psychometric analysis of the three item loneliness scale in the Czech Republic Zdenek Meier1, Lukas Novak1,2*, Jakub Helvich3, Patrik Licka1 and Peter Tavel1 Abstract Background There is a growing importance of loneliness measurement through valid and reliable instruments. However, to establish valid and reliable measures, there is a need to explore their psychometric properties in different research settings and language environments. For this reason, this study aimed to validate the Three Item Loneliness Scale (TILS) in the Czech Republic within a Slavonic language environment. Methods A sample of Czech adults (n = 3236) was used consisting primarily of university students. We utilized Classical Test Theory to assess TILS internal consistency, temporal stability, and factor structure. Item Response Theory (IRT) was used to estimate Differential Item Functioning (DIF), the discrimination and difficulty of the TILS items and to estimate the measurement precision of the whole scale. Construct validity was explored through the Spearman correlation coefficient using personality traits, depression, and anxiety. Results The results showed satisfactory reliability and validity of the TILS in the Czech Republic. The scale’s internal consistency and temporal stability were found to be satisfactory (Cronbach’s α = 0.81, McDonald’s ω = 0.82, ICC = 0.71). The parallel analysis supported the unidimensionality of the TILS. The IRT results indicated that the highest measurement precision was reached in individuals with lower and above-average levels of loneliness. Significant correlations between the TILS scores, anxiety, depression, and personality traits supported the construct validity of the scale. Although the DIF analysis identified statistically significant differences in responses to items TILS_2 and TILS_3 based on education level and employment status (with no significant differences observed for TILS_1), the effect sizes of these differences were small. This indicates that, despite statistical significance, the practical impact on the scale’s validity across these groups is minimal. Conclusions The validated TILS provides a reliable and valid tool for assessing loneliness in the Czech Republic. Its brevity makes it a practical option for researchers and clinicians seeking to measure loneliness time-efficiently. Future studies should explore how adding new items could increase the measurement precision of the TILS. Keywords Loneliness, Measurement, TILS, Psychometric Properties, Validation, Item response theory *Correspondence: Lukas Novak Full list of author information is available at the end of the article © The Author(s) 2025. 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To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/. Meier et al. BMC Psychology (2025) 13:21 Introduction Loneliness can be defined as a subjectively perceived state of aversion resulting from a lack of interpersonal relationships that one would like to have and actually have [1]. For numerous individuals, loneliness manifests as a transient phenomenon. Nonetheless, a subset of the population encounters challenges in meeting their social requirements, leading to prolonged loneliness [2]. In the scholarly discourse on loneliness, a prevalent categorization delineates between emotional and social loneliness. This bifurcation stems from Weiss’s perspective on social needs, which posits that diverse social relationships cater to distinct social necessities [3]. Emotional loneliness emerges from an individual’s perceived absence of close emotional ties, encompassing elements such as emotional support, affection, and intimacy. It is characterized by sentiments of detachment, a perceived lack of individuals who truly comprehend and resonate with one’s feelings, and the absence of supportive figures in times of need. Conversely, social loneliness stems from a perceived deficiency in a broader social network, encapsulating facets of social integration and a sense of belonging. It manifests as a feeling of disconnection from one’s surroundings, a dearth of companions for casual interaction or seeking practical assistance, and an overall sense of not belonging to a particular group or community [4]. This bilateral nature of loneliness underscores the importance of discerning the extent to which individual facets are measured. This distinction is crucial for establishing criterion-related validity, allowing for meaningful comparisons on how accurately a measure is able to capture either emotional or social loneliness within the established theoretical framework. Research on loneliness has been increasing in recent years. The primary reason for this increased research interest is probably associated with its widespread and increasing prevalence. In general, the prevalence of loneliness among young people ranges from 9 to 14% and among older people from 18 to 24% in the European area [5]. In more detail, the percentage of loneliness among older adults ranges from more than 25% in Italy to 8% in Germany and the Netherlands [6, 7]. More importantly, according to the findings of the Cigna health insurance company, there was a 13% increase in loneliness in the United States from 2018 to 2020 [8]. The COVID-19 pandemic has also had a particular impact on loneliness, with data showing an increase in feelings of loneliness in all age groups during the pandemic, but especially in young adults [9, 10]. Many studies have shown that loneliness is related with mental and physical health [11]. Moreover, loneliness is associated with mortality and morbidity [12, 13]. In the field of mental health, a number of studies have revealed Page 2 of 15 that there is a negative relationship between loneliness and mental health among children [14] and adults [15]. In more detail, a large number of studies found that there is a positive link between loneliness and depression [16, 17], including meta-an (...truncated)