# theta.k

##### Population Parameter THETA using Expected Number of Alleles

This function computes the population parameter THETA using the expected number of alleles.

##### Usage

`theta.k(x, n = NULL, k = NULL)`

##### Arguments

- x
- a vector or a factor.
- n
- a numeric giving the sample size.
- k
- a numeric giving the number of alleles.

##### Details

This function can be used in two ways: either with a vector giving the
individual genotypes from which the sample size and number of alleles
are derived (`theta.k(x)`

), or giving directly these two
quantities (`theta.k(n, k)`

).

The argument `x`

can be either a factor or a vector. If it is a
factor, then it is taken to give the individual alleles in the
population. If it is a numeric vector, then its values are taken to be
the numbers of each allele in the population. If it is a non-numeric
vector, it is a coerced as a factor.

Both arguments `n`

and `k`

must be single numeric values.

##### Value

- a numeric vector of length one with the estimated theta.

##### Note

For the moment, no standard-error or confidence interval is computed.

##### References

Ewens, W. J. (1972) The sampling theory of selectively neutral
alleles. *Theoretical Population Biology*, **3**, 87--112.

##### See Also

*Documentation reproduced from package ape, version 2.1-1, License: GPL (>= 2)*