calculate visibility for each sibship and ego

Usage

get_visibility(
  ego.dat,
  ego.id,
  sib.dat,
  sib.frame.indicator,
  weight = "wwgt",
  age = "age.cat"
)

ego.dat: The ego dataset (likely produced by siblingsurvival::prep_dhs_sib_histories())
ego.id: String with the name of the column in sib.dat containing the survey respondent ID
sib.dat: The long-form sibling dataset (likely produced by siblingsurvival::prep_dhs_sib_histories())
sib.frame.indicator: String with the name of the column in sib.dat containing a 0/1 coded variable indicating whether or not each sib is in the frame population
weight: string with the name of the column in ego.dat and sib.dat containing the sampling weight. Defaults to wwgt
age: string with the name of the column in ego.dat containing the age group. Defaults to age.cat

A list with three entries:

ego_vis - a tibble with one row per ego and the ego-specific visibilities
ego_vis_agg - a tibble with per-(sex, age) visibility summaries
sib_res - a tibble with one row per reported sibling, along with tibble with a row for each survey respondent (each unique value of ego.id), and the number of sibs the respondent reported on the frame, including and not including herself

  # TODO write example code