Fig. 1.

Confirmatory factor analyses of the identified four-domain SNOT-22 structure by principal component analysis, including the four domains “nasal symptoms”, “otologic symptoms”, “sleep symptoms”, and “emotional symptoms”. Confirmatory factor analysis was performed with SPSS-24’s AMOS plugin based on the four-domain structure of the principal component analysis. Ellipsoids represent domains, gray rectangles represent SNOT-22 items and their item number, and circles represent error terms. Solid arrows and numeric values in white rectangles represent factor loadings. White rectangles with dashed lines and corresponding dashed arrows represent modification indices. Refer also to the main text and to Table 5