Table 1.

Descriptive statistics and correlations among different statistical indicators of intra-individual variability from the empirical data.

	Raw	Raw	Detr		Raw	Detr
	M	ISD 2	ISD 2	MSSD	ICV	ICV	φ 1(1)	φ 1(2)	φ 2(2)
Mean	12.04	6.00	5.80	8.12	0.43	0.42	0.15	0.14	0.02
S.D.	2.98	8.84	8.65	10.94	0.55	0.54	0.20	0.20	0.15
Raw M	1.00
Raw ISD2	0.66	1.00
Detr ISD2	0.62	0.99	1.00
MSSD	0.56	0.94	0.94	1.00
Raw ICV	0.51	0.96	0.96	0.94	1.00
Detr ICV	0.49	0.95	0.97	0.93	0.99	1.00
φ 1(1)	0.40	0.36	0.38	0.19	0.34	0.36	1.00
φ 1(2)	0.40	0.37	0.39	0.20	0.37	0.37	0.93	1.00
φ 2(2)	0.12a	0.12a	0.13a	0.16b	0.14b	0.14b	0.18	−0.02a	1.00

Note: Raw M: raw-score mean; Raw ISD²: raw-score intra-individual variance; Detr ISD²: detrended intra-individual variance, $IS{D}_e^2$; MSSD: mean square successive difference; Raw ICV: raw-score intra-individual coefficient of variation = $\frac{ObsIS{D}^2}{ObsM}$; Detr ICV: detrended intra- individual coefficient of variation = $\frac{DetrIS{D}^2}{DetrM}$; φ₁(₁): auto-regressive parameter from the AR(1) model; φ₁(₂) and φ₂(₂): 1st order and 2nd order auto-regressive parameters from the AR(2) model. a: not significant at the .05 level. b: significant at the .05 level but not at the .01 level. All other correlations are significant at the .01 level.