A comparison of an emergent factor structure of the Insomnia Severity Index set against a global context

Study objectives: To identify the factor structure of the Insomnia Severity Index (ISI) and test it against competing international measurement models. Methods: A cross-sectional study survey with a randomly selected sample of 1,500 individuals living in Jordan. The ISI was administered and a response rate of 84% (n = 1,260) obtained. Both exploratory and confirmatory factor analysis were used to examine competing theoretical measurement models. Results: A new emergent measurement model was identified that may help synchronize differing measurement models reported in international literature. Exploratory factor analysis results indicated a two-factor model as a reasonably sound explanation of the data. However, this model is challenged by results from a confirmatory factor analysis. Conclusions: These findings expand the evidence base that the ISI is a reliable instrument to detect severity of insomnia in the population. Our model helps synthesize previous approaches to measurement reported in the international literature.