Description Usage Arguments Details Value Note Author(s) See Also Examples

'LL.2' and 'LL2.2' provide the two-parameter log-logistic function where the lower limit is fixed at 0 and the upper limit is fixed at 1, mostly suitable for binomial/quantal responses.

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`upper` |
numeric value. The fixed, upper limit in the model. Default is 1. |

`fixed` |
numeric vector. Specifies which parameters are fixed and at what value they are fixed. NAs for parameter that are not fixed. |

`names` |
a vector of character strings giving the names of the parameters. The default is reasonable. |

`...` |
Additional arguments (see |

The two-parameter log-logistic function is given by the expression

* f(x) = \frac{1}{1+\exp(b(\log(x)-\log(e)))}*

or in another parameterisation

* f(x) = \frac{1}{1+\exp(b(\log(x)-e))}*

The model function is symmetric about the inflection point (*e*).

See `llogistic`

.

This function is for use with the function `drm`

.

Christian Ritz

Related functions are `LL.3`

, `LL.4`

, `LL.5`

and the more general
`llogistic`

.

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