Here is more information on the equation. It is a growth function: Growth = a + b*(1-exp(-k*time))
where a, b and k are parameters. I wanted to test the difference in total growth between treatments and the parameters a + b represent total growth. Thus, I figured that I could add the parameters and the SE to test the treatment differences. I also need the rate constant k and the initial values a and their treatment differences. I found the equation I posted on this website: http://sci.tech-archive.net/Archive/sci.math/2004-07/4780.html This book was referenced: Kendall & Stuart's Advanced Theory of Statistics Thanks for all you your help. Adele From: ml-node+3477116-1659458804-211...@n4.nabble.com [mailto:ml-node+3477116-1659458804-211...@n4.nabble.com] Sent: Tuesday, April 26, 2011 09:29 PM To: Thompson, Adele - adele_thomp...@cargill.com Subject: Re: How can I extract information from list which class is nls On Tue, Apr 26, 2011 at 2:21 PM, Schatzi <[hidden email]</user/SendEmail.jtp?type=node&node=3477116&i=0&by-user=t>> wrote: > How do I extract the standard error of the parameter estimates? > > Also, if I would like to add two parameters together (x+y), can I use this > equation to calculate the new standard error?: > x = parameter 1 > y = parameter 2 > xSE = SE parameter 1 > ySE = SE parameter 2 > > NewSE=(x+y)*sqrt((xSE/x)^2+(ySE/y)^2) Try taking the square roots of their variance: > example(nls) > sqrt(diag(vcov(fm1DNase1))) Asym xmid scal 0.07815395 0.08135321 0.03227080 > > # it gives the same result as another solution > # offered on this thread > coef(summary(fm1DNase1))[, "Std. Error"] Asym xmid scal 0.07815395 0.08135321 0.03227080 -- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com ______________________________________________ [hidden email]</user/SendEmail.jtp?type=node&node=3477116&i=1&by-user=t> 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. ________________________________ If you reply to this email, your message will be added to the discussion below: http://r.789695.n4.nabble.com/How-can-I-extract-information-from-list-which-class-is-nls-tp804151p3477116.html To unsubscribe from How can I extract information from list which class is nls, click here<http://r.789695.n4.nabble.com/template/NamlServlet.jtp?macro=unsubscribe_by_code&node=804151&code=YWRlbGVfdGhvbXBzb25AY2FyZ2lsbC5jb218ODA0MTUxfC03MzgxNjM2NTM=>. ----- In theory, practice and theory are the same. In practice, they are not - Albert Einstein -- View this message in context: http://r.789695.n4.nabble.com/How-can-I-extract-information-from-list-which-class-is-nls-tp804151p3478123.html Sent from the R help mailing list archive at Nabble.com. [[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.
