[R] fitting logit to data

Philipp Pagel
Mon, 21 Feb 2011 16:25:41 -0000

On Mon, Feb 21, 2011 at 12:13:09PM +0100, Sylvia Tippmann
wrote:
> Hello,
>
> I'd like to fit a logit function to my data.
> The data is distributed like a logit (like in this plot on wikipedia
http://en.wikipedia.org/wiki/File:Logit.png)
> but the values on the x-axis are not between 0 and 1.
> I don't think using a glm is the solution because I simply want to
> infer the parameters of the logit function
> (offset, compression, slope...), so I can apply it to all my values on
> x and get my value y.

Two ideas:

1) scale your data so it does fit in [0,1] before fitting a glm

2) Use nls() to fit whatever function you find suitable

cu
	Philipp

--
Dr. Philipp Pagel
Lehrstuhl f?r Genomorientierte Bioinformatik
Technische Universit?t M?nchen
Wissenschaftszentrum Weihenstephan
Maximus-von-Imhof-Forum 3
85354 Freising, Germany