The Scale of Excessive Use of Social Networking Sites – the psychometric characteristics and validity of a proposed tool

Introduction
The paper describes the process of developing a tool to measure social networking site addiction among adolescents, that is the Scale of Excessive Use of Social Networking Sites (SEUS).

Material and methods
Three studies (Study 1, N = 587; Study 2, N = 351; Study 3, N = 1054) were performed to establish psychometric properties, construct and criterion validity of SEUS among Polish high school students. Two different versions of SEUS were developed (48- and 30-item). Their results were correlated with the Bergen Facebook Addiction Scale (BFAS) and standardised questionnaires for measuring psychological variables.

Results
SEUS construct validity was checked with Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) procedures. The long 48-item version was reduced to 14 items on which SEUS-14 is based. The final one-factor solution explained 57.7% of variance. The reliability measured with Cronbach’s α is very good. SEUS-14 correlates with BFAS and psychological measures of personality traits, narcissism, self-esteem and Behavioural Activation System, which confirms the scale criterion validity.

Discussion
The presented study findings are consistent with the results of other research on Facebook or internet addiction. Regarding the construct validity, one-factor solution turned out to be the best while correlation analysis confirmed SEUS criterion validity.

Conclusions
SEUS-14 has demonstrated good psychometric properties in a national sample of Polish adolescents. The measure, treated as a screening tool, can be used for scientific purpose though further studies on the broader use of the scale are necessary.