> print(fit.r)
Inference for Stan model: cox.
3 chains, each with iter=10000; warmup=3000; thin=1;
post-warmup draws per chain=7000, total post-warmup draws=21000.

             mean se_mean    sd      2.5%       25%       50%       75%     97.5% n_eff Rhat
beta0        2.56    0.00  0.05      2.47      2.53      2.56      2.59      2.65   765    1
beta1        0.20    0.00  0.01      0.17      0.19      0.20      0.21      0.23   670    1
sigma_r      1.29    0.00  0.03      1.22      1.26      1.29      1.31      1.35 21000    1
lp__    164065.17    0.29 22.89 164018.73 164050.14 164065.79 164080.74 164108.63  6316    1