# Extrapolates non-extinct cohorts

### Description

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.

### Usage

1 |

### Arguments

`path` |
path to the HMD folder for local access |

`max` |
age at which the data should be right-censored |

`country` |
HMD population letter code |

`year` |
birth cohort for which the extrapolation should be performed |

`sex` |
sex for which the extrapolation should be performed ("females" or "males") |

`cmx` |
observed cohort mortality rates as given by a call to the readHMD function from the HMDHFDplus package |

### Details

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.

### Value

Returns a vector of age-specific cohort mortality rates whose length depends on the `max`

argument

### References

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.

### See Also

HMD2MH, fdm from the demography package