Re: [R] How can I extract information from list which class is nls

2011-04-27 Thread Schatzi
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

Re: [R] How can I extract information from list which class is nls

2011-04-27 Thread David Winsemius
On Apr 27, 2011, at 9:28 AM, Schatzi wrote: 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

Re: [R] How can I extract information from list which class is nls

2011-04-27 Thread Schatzi
It is not a human growth curve. The parameter estimates are about: a = .5 b = 7 k = 1 It is not a sigmoidal curve as there is never a concave segment. From: ml-node+3478241-1447170361-211...@n4.nabble.com [mailto:ml-node+3478241-1447170361-211...@n4.nabble.com] Sent: Wednesday, April 27, 2011

Re: [R] How can I extract information from list which class is nls

2011-04-26 Thread Schatzi
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

Re: [R] How can I extract information from list which class is nls

2011-04-26 Thread Joshua Wiley
Hi, One way would be: summary(nls.object)[[coefficients]][, Std. Error] If you have a hankering to do it yourself rather than go through the summary formula, the code here will get you there: getAnywhere(summary.nls) If you are going to be doing it a lot, creating a little function might be

Re: [R] How can I extract information from list which class is nls

2011-04-26 Thread Peter Ehlers
On 2011-04-26 15:11, Joshua Wiley wrote: Hi, One way would be: summary(nls.object)[[coefficients]][, Std. Error] If you have a hankering to do it yourself rather than go through the summary formula, the code here will get you there: getAnywhere(summary.nls) If you are going to be doing it a

Re: [R] How can I extract information from list which class is nls

2011-04-26 Thread Joshua Wiley
I would generally use the coef() extractor function if it's available (and it is for nls()). ?nls has an example:  coef(summary(fm1DNase1)) I knew about coef() on model objects, but I did not know it had methods for their summaries. What wonderful information! Josh which is a matrix from

Re: [R] How can I extract information from list which class is nls

2011-04-26 Thread Gabor Grothendieck
On Tue, Apr 26, 2011 at 2:21 PM, Schatzi adele_thomp...@cargill.com 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