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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