TABLE VI.A.2.

Functional status and health-related QOL questionnaires

	Internal consistencya	Test–retest reliabilityb	Measurement error	Convergent validityc	Divergent validity	Discriminative validity	Responsiveness
ESS	Acceptable	**	–	Poor to moderate	–	Present	–
PSQI	Acceptable	**	–	Strong	Presentd	Present	–
SAQLI	Excellent	Excellent	–	Moderate	–	–	Present
FOSQ	Excellent	Excellent	–	Moderate	–	Present	Present

Abbreviations: – Not reported;

^**not clearly assessed. ESS, Epworth Sleepiness Scale; FOSQ, functional outcomes sleep questionnaire; PSQI, Pittsburgh sleep quality index; SAQLI, sleep apnea quality of life index.

^aBased on Cronbach’s α values: unacceptable (α < 0.5), poor (0.5 ≤ α < 0.6), questionable (0.6≤ α <0.7), acceptable (0.7 ≤ α < 0.8), good (0.8 ≤ α < 0.9), excellent (α ≥ 0.9).

^bBased on intraclass correlation values: poor (ICC < 0.5), moderate (0.5 ≤ ICC < 0.75), good (0.75 ≤ ICC < 0.9), excellent (ICC ≥ 0.9).

^cReported as degree of correlation with questionnaires measuring related constructs: poor (r < 0.3), moderate (0.3 ≤ r < 0.7), strong (r ≥ 0.7).

^dIndicates presence of poor or non-significant correlations with unrelated questionnaires.