Computational Intelligence and Neuroscience

Research Article

Effects of Between- and Within-Subject Variability on Autonomic Cardiorespiratory Activity during Sleep and Their Limitations on Sleep Staging: A Multilevel Analysis

Table 6

Variances of a sequence of models (Models A–G in the appendix) with different effects for computing their PVE for the six cardiorespiratory parameters analyzed in this study.


Models A–G with different effects (see the appendix)	Respiratory parameters		Cardiac parameters
Models A–G with different effects (see the appendix)	BR, ln-Hz	SDBR, ln-Hz	HR, ln-bpm	SDNN, ln-ms	LF, nu	HF, nu

Model A: baseline model
	0.0229	0.3306	0.0043	0.2626	0.0354	0.0356
	0.0328	0.1389	0.0192	0.2997	0.0151	0.0156
Dev	−125045	232926	−348717	202249	−66487	−65952

Model B: Model A + within-subject time effect (fixed)
	0.0228	0.3284	0.0040	0.2600	0.0353	0.0355
	0.0328	0.1393	0.0191	0.2999	0.0150	0.0155
Dev	−125109	232056	−357783	200926	−66724	−66131

Model C: Model B + demographic effect (fixed)
	0.0228	0.3284	0.0040	0.2600	0.0353	0.0355
	0.0308	0.1329	0.0183	0.2230	0.0147	0.0136
Dev	−125120	232048	−357790	200877	−66730	−66152

Model D: Model C + centering effect (fixed)
	0.0228	0.3284	0.0040	0.2600	0.0353	0.0355
	0.0001	0.0098	0.0001	0.0033	0.0003	0.0002
Dev	−126064	231624	−358718	200200	−67367	−66850

Model E: Model D + demographic-related time effect (fixed)
	0.0227	0.3284	0.0040	0.2597	0.0352	0.0354
	0.0001	0.0098	0.0001	0.0033	0.0003	0.0002
Dev	−126393	231624^Ne	−358718^Ne	200027	−67718	−67206

Model F: Model E + between-subject time effect (random)
	0.0210	0.3157	0.0034	0.2476	0.0343	0.0346
	0.0003	0.0097	0.0001	0.0041	0.0003	0.0002
	1.1e − 7	7.3e − 7	3.6e − 8	7.1e − 7	5.2e − 8	4.5e − 8
Dev	−136185	226933	−380964	194316	−70913	−69899

Model G: Model F + between-subject physiological effect (random)
	0.0186	0.2896	0.0029	0.2298	0.0328	0.033
	0	0	0	0	0	0
	1.0e − 7	6.7e − 7	3.5e − 8	7.1e − 7	4.8e − 8	4.3e − 8
Dev	−151084	216874	−398866	185774	−75617	−74903

Note: ln, natural logarithm; nu, normalized unit; Dev, model deviance; Ne, no effect. All the models include fixed () and random () intercepts, and sleep-stage-dependent variables (wake, REM, light, and deep) with their coefficients. The models were optimized by excluding the effects with their coefficients statistically equal to zero (Wald -test, ) and the variances presented in the table were all statistically significant (Wald -test, ).