Call:
ddhazard(formula = survival::Surv(stop, event) ~ group, data = head_neck_cancer, 
    by = 1, max_T = 20, a_0 = rep(0, 2), Q_0 = diag(1, 2), Q = diag(0.1, 
        2), order = 1, control = ddhazard_control(eps = 0.1))

'logit' model fitted with the 'EKF' method in 2 iterations of the EM algorithm.

Smoothed time-varying coefficients are:
   (Intercept)       sd     group1       sd 
 0   -2.806424 0.4064023 0.1519309 0.4488750
 2   -2.882709 0.3038966 0.1967654 0.3681009
 4   -2.493780 0.3060795 0.3738359 0.3596999
 6   -2.220863 0.2842865 0.6247045 0.3420799
 9   -2.888184 0.3244203 0.5569002 0.3892709
11   -3.211450 0.3551100 0.4901311 0.4309866
13   -3.398163 0.3907957 0.6133135 0.4794959
16   -3.455511 0.4285787 0.7508514 0.5382961
18   -3.479997 0.4831253 0.8774581 0.6095133
20   -3.421549 0.5820568 1.0707865 0.7075980

The estimated diagonal entries of the covariance matrix in the state equation are:
(Intercept)      group1 
 0.10291497  0.09050972 

96 individuals used in estimation with 65 observed events.
