undo_pr {vital}

Undo a product/ratio transformation

Description

Make a new vital from products and ratios of a measured variable by a key variable. The most common use case of this function is for computing mortality rates by sex, from the sex ratios and geometric mean of the rates.

Usage

undo_pr(.data, .var, key = Sex, times = 2000)

Arguments

.data

A vital object

.var

A bare variable name of the measured variable to use.

key

A bare variable name specifying the key variable to use. This key variable must include the value geometric_mean.

times

When the variable is a distribution, the product must be computed by simulation. This argument specifies the number of simulations to use.

Details

Note that when a measured variable takes value 0, the geometric mean is set to 10^-6 to avoid infinite values in the ratio. Therefore, when the transformation is undone, the results will not be identical to the original in the case that the original data was 0.

Value

A vital object

References

Hyndman, R.J., Booth, H., & Yasmeen, F. (2013). Coherent mortality forecasting: the product-ratio method with functional time series models. Demography, 50(1), 261-283.

Examples

# Make products and ratios
orig_data <- aus_mortality |>
  dplyr::filter(Year > 2015, Sex != "total", Code == "NSW")
pr <- orig_data |>
  make_pr(Mortality)
# Compare original data with product/ratio version
orig_data
pr
# Undo products and ratios
pr |> undo_pr(Mortality)