# Birth year probabilities

`CalcBYprobs.Rd`

Estimate the probability that an individual with unknown birth
year is born in year `y`

, based on `BirthYears`

or `BY.min`

and/or `BY.max`

of its parents, offspring, and siblings, combined with
`AgePrior`

(the age distribution of other parent-offspring pairs),
and/or `Year.last`

of its parents.

## Arguments

- Pedigree
dataframe with columns id-dam-sire.

- LifeHistData
data.frame with up to 6 columns:

- ID
max. 30 characters long

- Sex
1 = female, 2 = male, 3 = unknown, 4 = hermaphrodite, other numbers or NA = unknown

- BirthYear
birth or hatching year, integer, with missing values as NA or any negative number.

- BY.min
minimum birth year, only used if BirthYear is missing

- BY.max
maximum birth year, only used if BirthYear is missing

- Year.last
Last year in which individual could have had offspring. Can e.g. in mammals be the year before death for females, and year after death for males.

"Birth year" may be in any arbitrary discrete time unit relevant to the species (day, month, decade), as long as parents are never born in the same time unit as their offspring, and only integers are used. Individuals do not need to be in the same order as in `GenoM', nor do all genotyped individuals need to be included.

- AgePrior
a matrix with probability ratios for individuals with age difference A to have relationship R, as generated by

`MakeAgePrior`

. If`NULL`

,`MakeAgePrior`

is called using its default values.

## Value

A matrix with for each individual (rows) in the pedigree that has a missing
birth year in `LifeHistData`

, or that is not included in

`LifeHistData`

, the probability that it is born in `y`

(columns).
Probabilities are rounded to 3 decimal points and may therefore not sum
exactly to 1.

## Details

This function assists in estimating birth years of individuals for which these are unknown, provided they have at least one parent or one offspring in the pedigree. It is not a substitute for field-based estimates of age, only a method to summarise the pedigree + birth year based information.

## WARNING

Any errors in the pedigree or lifehistory data will cause errors in the birth year probabilities of their parents and offspring, and putatively also of more distant ancestors and descendants. If the ageprior is based on the same erroneous pedigree and lifehistory data, all birth year probabilities will be affected.

## See also

`MakeAgePrior`

to estimate effect of age on
relationships.