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          -3   0.4    0.2   0.4
 2          -3   0.3    0.2   0.4
 4          -2   0.3    0.4   0.4
 6          -2   0.3    0.6   0.3
 9          -3   0.3    0.6   0.4
11          -3   0.4    0.5   0.4
13          -3   0.4    0.6   0.5
16          -3   0.4    0.8   0.5
18          -3   0.5    0.9   0.6
20          -3   0.6    1.1   0.7

The estimated diagonal entries of the covariance matrix in the state equation are:
(Intercept)      group1 
       0.10        0.09 

96 individuals used in estimation with 65 observed events.
