# theta.s

From ape v2.1-1
by Emmanuel Paradis

##### Population Parameter THETA using Segregating Sites in DNA Sequences

This function computes the population parameter THETA using the
number of segregating sites `s`

in a sample of `n`

DNA sequences.

##### Usage

`theta.s(s, n, variance = FALSE)`

##### Arguments

- s
- a numeric giving the number of segregating sites.
- n
- a numeric giving the number of sequences.
- variance
- a logical indicating whether the variance of the
estimated THETA should be returned (
`TRUE`

), the default being`FALSE`

.

##### Value

- a numeric vector of length one with the estimated theta (the default),
or of length two if the standard error is returned
(
`variance = TRUE`

).

##### Note

The number of segregating sites needs to be computed beforehand, for
instance with the function `seg.sites`

(see example below).

##### References

Watterson, G. (1975) On the number of segragating sites in genetical
models without recombination. *Theoretical Population Biology*,
**7**, 256--276.

Tajima, F. (1989) Statistical method for testing the neutral mutation
hypothesis by DNA polymorphism. *Genetics*, **123**, 585--595.

##### See Also

##### Examples

```
data(woodmouse)
y <- seg.sites(woodmouse)
s <- length(y)
n <- length(woodmouse)
theta.s(s, n)
theta.s(s, n, variance = TRUE)
```

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

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