This is an internal function of package MortHump which extrapolates cohort mortality rates for non-extinct cohorts. It is meant to be called from the HMD2MH function.
xtp(path, max, country, year, sex, cmx)path to the HMD folder for local access
age at which the data should be right-censored
HMD population letter code
birth cohort for which the extrapolation should be performed
sex for which the extrapolation should be performed ("females" or "males")
observed cohort mortality rates as given by a call to the readHMD function from the HMDHFDplus package
Returns a vector of age-specific cohort mortality rates whose length depends on the max argument
The extrapolation is currently only available for females and males, not for the total population. The function uses the model of Hyndman & Ullah (see reference), a variant of the Lee-Carter model which, among others, takes into account more than one dimension of the single value decomposition.
The function first fits the model to period data, then extrapolates the age-specific death rates in the future, and reconstruct the cohort asdr by extracting the diagonal of the period asdr.
Hyndman, R. J., & Ullah, M. S. (2007). Robust forecasting of mortality and fertility rates: a functional data approach. Computational Statistics & Data Analysis, 51(10), 4942-4956.