Retrieve baseline hazard rate and band index at a given attained age

Determines which attained-age band contains a given attained_age and returns both the band index and the corresponding baseline hazard rate.

Usage

.rate_and_band_at_age(attained_age, lookup_table, tol = 1e-12)

Arguments

attained_age: Numeric scalar giving the current attained age.
lookup_table: List containing numeric vectors lo, hi, and rate, defining the lower bounds, upper bounds, and baseline hazard rates for each age band.
tolerance: Small non-negative numeric scalar used when comparing attained_age to band boundaries.

Value

A list with components:

band_index: Integer index of the age band containing attained_age.
baseline_rate: Numeric scalar baseline hazard rate for the identified band.

If attained_age lies outside the support of the age bands, both elements are returned as NA.

Details

Age bands are defined by lookup_table$lo and lookup_table$hi and are treated as left-closed, right-open intervals: [lo, hi). The final band is treated as closed on the right to ensure coverage of its upper boundary.

A numerical tolerance is used to avoid instability at band boundaries due to floating-point rounding.

Examples

lookup_table <- list(
  lo   = c(50, 60),
  hi   = c(60, 70),
  rate = c(0.01, 0.02)
)

.rate_and_band_at_age(attained_age = 55,
                      lookup_table = lookup_table)
#> Error in .rate_and_band_at_age(attained_age = 55, lookup_table = lookup_table): could not find function ".rate_and_band_at_age"