Background hazard
= Background hazard
{title2=$h_B^{(i)}(t)$}
In <relative survival>, the <background hazard> is an individual's expected mortality hazard in a suitable reference population. Its dependence on age, sex and calendar time can be obtained from population life tables. In a heterogeneous cohort, estimating a common <excess hazard> requires averaging these known <background hazards> over the current <risk set>, rather than over the original cohort.