Fitting a logistic function

[Torsten Ponik]

Dear all,

I am trying to fit a a logistic function to some (~20) data points. The function looks like this:

\[ f(x) = \frac{L}{1 + e^{-k(x - x_0)}} \] Basically, I need to estimate the parameters L, k and x_0 given my data. What method would you suggest to use in that case?

[Torsten Ponik]

Also (although not a Stata issue), I would have to invert the function afterwards using the estimated parameters. I´d appreciate any advice on that as well.

[Rich Goldstein]

have you looked at the examples of estimating a logistic function in the manual and help file for -nl-? see

h nl

[Torsten Ponik]

Thanks Rich, I´ll have a look at that