Life table -> lt_abridged() failing for life tables starting at later ages

[Chydide]

Hi Tim and team,

I have been trying to use the lt_abridged() function to obtain an abridged life table estimates starting at age 20 and over, the function seems to be generating an error indicating a missing column, I have added a quick example:

lt_abridged(
Age = seq(20, 85, 5),
nMx = c(0.001, 0.0012, 0.0015, 0.002, 0.003, 0.004, 0.005, 0.007, 0.009, 0.015, 0.025, 0.045, 0.065, 0.090),
Sex = "f")

Could you please help.

Regards,
Chido

[timriffe]

Hi Chido,
Unfortunately lt_abridged() is hard-coded for age to start at 0, sorry this is causing headache. If I understand correctly, the nMx you use have been extracted from a model life table? If so, try using ages from 0 onward. If ages 20+ are of interest, you can then truncate the lower age range. The columns you'd need to adjust to truncate properly would be: lx, nLx, and ndx, whereas the other columns would remain the same. Here using example data from lt_abrdiged():

library(tidyverse)
library(DemoTools)
Exposures <- c(100958,466275,624134,559559,446736,370653,301862,249409,
 		247473,223014,172260,149338,127242,105715,79614,53660,
 		31021,16805,8000,4000,2000,1000)

Deaths <- c(8674,1592,618,411,755,1098,1100,1357,
 		1335,3257,2200,4023,2167,4578,2956,4212,
 		2887,2351,1500,900,500,300)
 
nMx <- Deaths / Exposures
 # lower age bounds
Age    <- c(0, 1, seq(5, 100, by = 5))

LT <- lt_abridged(nMx=nMx,
 		Age = Age,
 		axmethod = "un")
 
radix <- 1e5

# now recondition to start lifetable at age 20
LT |> 
  filter(Age >= 20) |> 
  mutate(lx = radix * lx / lx[1],
         ndx = radix * ndx / lx[1],
         nLx = radix * nLx / lx[1])

I'm just assuming you have the possibility to include nMx from age 0 because I see model life table in the issue title. If this is not the case, then you could pad the left side of your nMx with fake-but-plausible values for ages [0,1,5,10,15]. Then, calculate the full abridged lifetable and truncate. If you'll need to do this a lot, then it may be worth your time to write a wrapper function that handles this non-aesthetic bookkeeping. Of course, we could modify lt_abridged() to handle such cases, and this would be appreciated, but I don't have the time to do so at the moment.

[ikashnitsky]

#259