Fig. 1

Confirmatory factor analysis of the Epworth Sleepiness Scale (ESS) scores in Ethiopian university students. ESS_1 to ESS_8: Items of the ESS; A: 1-Factor model, B: 1-Factor model (Smith et al. 2008), C: 2-Factor model (Gelaye et al. 2014), D: 1-Factor model with incorporation of modification indices (co-varying error terms). All coefficients are standardized. Ovals latent variables, rectangles measured variables, circles error terms, single-headed arrows between ovals and rectangles factor loadings, single-headed arrows between circles and rectangles error terms. Smith SS, Oei TP, Douglas JA, Brown I, Jorgensen G, Andrews J. Confirmatory factor analysis of the Epworth Sleepiness Scale (ESS) in patients with obstructive sleep apnoea. Sleep medicine. 2008 Oct 1;9(7):739–44. Gelaye B, Lohsoonthorn V, Lertmeharit S, Pensuksan WC, Sanchez SE, Lemma S, Berhane Y, Zhu X, Vélez JC, Barbosa C, Anderade A. Construct validity and factor structure of the pittsburgh sleep quality index and epworth sleepiness scale in a multi-national study of African, South East Asian and South American college students. PloS one. SSS 31;9(12):e116383