title: Internet Gaming Disorder as a formative construct: Implications for conceptualization and measurement.
abstract: Some people have serious problems controlling their Internet and video game use. The DSM-5 now includes a proposal for 'Internet Gaming Disorder' (IGD) as a condition in need of further study. Various studies aim to validate the proposed diagnostic criteria for IGD and multiple new scales have been introduced that cover the suggested criteria. Using a structured approach, we demonstrate that IGD might be better interpreted as a formative construct, as opposed to the current practice of conceptualizing it as a reflective construct. Incorrectly approaching a formative construct as a reflective one causes serious problems in scale development, including: (i) incorrect reliance on item-to-total scale correlation to exclude items and incorrectly relying on indices of inter-item reliability that do not fit the measurement model (e.g., Cronbach's α); (ii) incorrect interpretation of composite or mean scores that assume all items are equal in contributing value to a sum score; and (iii) biased estimation of model parameters in statistical models. We show that these issues are impacting current validation efforts through two recent examples. A reinterpretation of IGD as a formative construct has broad consequences for current validation efforts and provides opportunities to reanalyze existing data. We discuss three broad implications for current research: (i) composite latent constructs should be defined and used in models; (ii) item exclusion and selection should not rely on item-to-total scale correlations; and (iii) existing definitions of IGD should be enriched further.
authors.affiliation: Department of Communication Sciences, iMinds-MICT-Ghent University, Ghent, Belgium.
authors.forename: Antonius J
authors.initials: AJ
authors.lastname: van Rooij
authors.affiliation: Department of Communication Sciences, iMinds-MICT-Ghent University, Ghent, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: Van Looy
authors.affiliation: Laboratory for Experimental Psychopathology, Psychological Science Research Institute, Catholic University of Louvain, Louvain-la-Neuve, Belgium.|Department of Adult Psychiatry, Internet and Gambling Disorders Clinic, Saint-Luc University Hospital, Brussels, Belgium.
authors.forename: Joël
authors.initials: J
authors.lastname: Billieux
mesh_terms: D016739:Behavior, Addictive / Q000175:diagnosis*; D006801:Humans; D020407:Internet; D011594:Psychometrics; D018910:Video Games / Q000009:adverse effects* / Q000523:psychology*
keywords: 
  Internet Gaming Disorder; formative measurement model; psychometrics; reflective measurement model; validation