[R] Need to replicate Boltzman Signmodial Curve fit from Graph Pad

R. Michael Weylandt michael.weylandt at gmail.com
Tue Apr 23 18:45:51 CEST 2013

On Tue, Apr 23, 2013 at 3:55 PM, J J <rnoobier at gmail.com> wrote:
> Hello useRs (please don't kill me),
> I've fairly new to R having only a few months of playing around with R.
> What little I've learned has been extremely useful.
> If someone could point me as to how to replicate the Boltzman Sigmodial
> curve fit as provided by Graphpad software I'd be eternally grateful.
> Where  we currently use Graphpad for only this one function,its seems
> highly inefficient for a $100 piece of software to be used for only one
> function (which isn't nearly as bad as the company's pandemic reliance on
> Excel for nearly everything else).
> so anyway, what I'd normally do is take a set of data like this:
>  pH counts  3.8 968  5.0 1347  5.8 2867  6.6 9203  7.0 15817  7.4 20297  8.2
> 31916  9.2 35756
> then fit this to a Boltzman sigmodial in Graphpad. Graphpad spits out a
> much longer set of vectors and also information about v50 and confidence
> intervals etc (if anyone is familiar with that software). This is what i'd
> like to replicate.
> It might be that I just don't know what i'm doing,so feel free to call me
> an idiot but any help is greatly appreciated!

Being unfamiliar with the problem domain, I'd imagine that nls() would
probably be what you're looking for. Does

? nls

seem promising? If so, we can help you get started.


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