. 2019 Oct 30;7(10):e13978. doi: 10.2196/13978

Table 6.

Random effects of the linear multilevel model evaluating the time trend of perceived stress- levels (PSS-4) while using TrackYourStress including the 5 subscales of the Perceived Stress Reactivity Scale as z-standardized time-invariant covariates.

Random effects	Estimate	SE	Values
Random effects	Estimate	SE	Wald Z test	P value
Var(Residual)	2.248	0.218	10.325	<.001
Var(Intercept)	5.731	1.131	5.069	<.001
Cov(Intercept; time)	−0.061	0.037	−1.651	.10
Var(Time)	0.007	0.002	3.260	.001

^aPSRS: Perceived Stress Reactivity Scale.