I think you'll find that this is just an alternate parameterization of a 4 P logistic. ... and in any case there is no statistically detectable difference between the two.
That is, this is just basically a Graphpad marketing ploy. Fit such data with anyone's logistic function ... and that is probably overfitting in many cases, anyway. Cheers, Bert On Tue, Apr 23, 2013 at 9:54 AM, John Kane <jrkrid...@inbox.com> wrote: > No idea of the area but does this link help? > http://bioinformatics.oxfordjournals.org/content/24/13/1549.full > > John Kane > Kingston ON Canada > > >> -----Original Message----- >> From: rnoob...@gmail.com >> Sent: Tue, 23 Apr 2013 10:55:59 -0400 >> To: r-help@r-project.org >> Subject: [R] Need to replicate Boltzman Signmodial Curve fit from Graph >> Pad >> >> 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! >> >> -JJ >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> R-help@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide >> http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. > > ____________________________________________________________ > FREE 3D EARTH SCREENSAVER - Watch the Earth right on your desktop! > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. -- Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
