niversity of Oxford, via
Dept of Statistics Consulting Service
</p>


<h3>Examples</h3>

<pre><code class='language-R'># Fit logistic curve from p = 0.5 to p = 1.0
fp1 &lt;- deriv(~ 0.5 + 0.5/(1 + exp(-(x-L75)/scal)),
             c("L75", "scal"),
             function(x,L75,scal)NULL)
nls(Correct/Trials ~ fp1(Loud, L75, scal), data = OME,
    start = c(L75=45, scal=3))
nls(Correct/Trials ~ fp1(Loud, L75, scal),
    data = OME[OME$Noise == "coherent",],
    start=c(L75=45, scal=3))
nls(Correct/Trials ~ fp1