Table 11.

Regression analysis prediction of a stress symptom composite from digital biomarker variables, with covariance for age and gender.

		B	Std. Error	β	t	Sig.	R	ΔR²
Model 1	(Constant)	34.266	10.237		3.347	0.002	0.235	0.008
	Age	1.628	1.096	0.232	1.486	0.145
	Sex	1.758	2.793	0.098	0.629	0.533
Model 2 Step 1	(Constant)	48.686	11.670		4.172	<.001	0.405	0.099
	Age	1.653	1.044	0.236	1.583	0.121
	Sex	1.609	2.662	0.090	0.604	0.549
Step 2	pNN50	-1.453	.646	-0.330	-2.250	0.03

pNN50, The proportion of NN50 divided by the total number of NN (R-R) intervals.