Unidimensionality
The criterion of unidimensionality was fulfilled, as demonstrated by the PCA of the residuals. The first component of the PCA had an eigenvalue of 2.244 and accounted for 18.7% of the variance. In addition, structural validity was demonstrated by confirmatory factor analysis for the HidroQoL overall scale. With a CFI of 0.811, a TLI of 0.786, an RMSEA of 0.099, and an SRMR of 0.063, the scale met at least one COSMIN criterion for sufficient structural validity.