On Apr 23, 2013, at 18:45 , R. Michael Weylandt wrote: > On Tue, Apr 23, 2013 at 3:55 PM, J J <rnoob...@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.
In particular, SSfpl looks tantalizingly similar to the Bolzmann sigmoidal (sic!) curve. -- Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Email: pd....@cbs.dk Priv: pda...@gmail.com ______________________________________________ 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.
