similar to: info

Dear R users I'm a new user of R and I have a basic question about the 4-parameter logistic model. According to the information from Pinheiro & Bates the model is: y(x)=theta1+(theta2-theta1)/(1+exp((theta3-x)/theta4)) == y(x)=A+(B-A)/(1+exp((xmid-input)/scal)) from the graph in page 518 of the book of the same authors (mixed models in S) theta 1 corresponds to the horizontal asymptote

Hi R help, I am trying to determine how nls() generates a function based on the self-starting SSlogis and what the formula for the function would be. I've scoured the help site, and other literature to try and figure this out but I still am unsure if I am correct in what I am coming up with. ************************************************************************** dat <-

Dear R-help subscribers Would you tell me how to apply SSfpl with binary data as below? Unfortunately, there is not the EXAMPLE in help(SSfpl) for binary data but for quantitative data(Chick). V1: dose V2: log-transformed dose V3: response (rate) V1 V2 V3 1 0.775 -0.2548922 0.1666667 2 5.000 1.6094379 0.8148148 3 10.000 2.3025851 0.5000000 4 20.000 2.9957323

Hi, I was hoping to get some advice on how to derive estimates of slopes from four parameter logistic models fit with SSfpl. I fit the model using: model<-nls(temp~SSfpl(time,a,b,c,d)) summary(model) I am interested in the values of the lower and upper asymptotes (parameters a and b), but also in the gradient of the line at the inflection point (c) which I assume tells me my rate of

Hi I am struggling to fit a non-linear trend using the likfit function in geoR. Specifically I want a sigmoidal function, something like SSfpl in the nls package to fit the trend. But it seems trend.spatial in geoR only works with lm or glm type models. Any ideas how I can specify the model to calculate the kriging parameters using REML, including the parameters of a sigmoidal trend function

I'm running a simulation that uses nls on each run. Sometimes, not unexpectedly, nls doesn't return parameter estimates (e.g., "singular gradient" error). Of course when this happens the simulation (in a loop) stops and no results are recorded. What I would like is for the simulation to simply record that nls couldn't obtain estimates on a particular run due to whatever

I'm trying to do a sort of home-brew item-characteristic-curve. This is a plot of the probability of getting a test item correct, as a function of the mean score on the test. (The last part is the home brew part.) Logistic regression with glm would work nicely, EXCEPT for the fact that the curve requires a guessing parameter. So the asymptote on the left is not 0 but rather something like

Recently I have been building LLVM and Clang from the distribution using gcc 4.9.2. With the new 5.0.0 rc2 that is giving warning messages during the compilation. I have been trying out some other compilers. gcc 5.2 with -std=c++11 This works, although there are still some warnings. gcc 6.4 and gcc 7.1 fail with errors such as this in building libcxxabi as follows: Command:

Hola, I am trying to isolate the memory leak I suspect in a mailman installation ? I found: http://blogs.sun.com/sanjeevb/date/200506 It gives an error: god at irt-smtp-02:~ 9:21am 65 # ./memleak.d 10312 dtrace: failed to compile script ./memleak.d: line 3: probe description pid10312:libc.so.1:malloc:entry does not match any probes I am on SunOS 5.10 Generic_127112-07 i86pc i386 i86pc Are

Hi, I'm trying to use Robust non-linear regression to fit dose response curves. Maybe I didnt look good enough, but I dind't find robust methods for NON linear regression implemented in R. A method that looked good to me but is unfortunately not (yet) implemented in R is described in http://www.graphpad.com/articles/RobustNonlinearRegression_files/frame.htm

It appears that Markdown will process ampersands contained within HTML comments if that comment is part of a markdown paragraph, but will not when that paragraph is contained within an HTML block of it's own (and therefore ignored by Markdown.) For example: This is a markdown paragraph with a comment that *will* be processed <!-- This & *will* be converted -->

I'm trying to fit a Gompertz sigmoid as follows: x <- c(15, 16, 17, 18, 19) # arbitrary example data here; y <- c(0.1, 1.8, 2.2, 2.6, 2.9) # actual data is similar gm <- nls(y ~ a+b*exp(-exp(-c*(x-d))), start=c(a=?, b=?, c=?, d=?)) I have been unable to properly set the starting value '?'s. All of my guesses yield either a "singular gradient" error if they

Dear users, I have a weird questions. A friend of mine, some years ago, supposedly trying to access help files without Internet connection, got something like this error message: "The Pythia is not available, please go to Delphi" When I've heard about it, I found it very funny and I'd like to be able to get it. Does anyone of you know how to get this error message again?

Dear users, My problem concerns save() within a for loop. Here is my code: for (i in 1:4) { temp <- data.frame(a=(i+1):(i+10), b=LETTERS[(i+1):(i+10)]) filename <- paste("file", i, sep="") assign(filename, temp) save(filename, file=paste(filename, ".rda", sep="")) } As you can see, save() doesn't work as I would like: (1) the object

Hi, The following lines in compat.c are rather imprudent: if (read_batch || write_batch) checksum_seed = 32761; else checksum_seed = time(NULL); write_int(f_out,checksum_seed); Setting checksum_seed to a constant in batch mode means block collisions are reproducible and predictable. Thus, some files will be permanently "unlucky" in batch mode and will

I see Intel has released a new tool. Oh, it requires some patches to the kernel to record latency times. Good thing people don''t mind patching their kernels, eh? So who can write the equivalent latencytop.d the fastest? ;-) http://www.latencytop.org/ -- cburgess at qnx.com

looks like my message from last week about writing tools was right on time... we are enjoying a display of fireworks now going off in this particular arena... fletcher started work on an editing app with markdown-preview built right in, after reporting on his blog that he had "seen the future" in ali's post last month, where ali debuted his syntax highlighter, and fletcher is

Is there any way to pursuade markdown to create HTML link anchor targets? -- Make April 15 just another day, visit http://fairtax.org

Dear all I am struggling to fit data which form something like CDF by lognorm. Here are my data: proc <- c(0.9, 0.84, 0.5, 0.16, 0.1) size <- c(0.144, 0.172, 0.272, 0.481, 0.583) plot(size, proc, xlim=c(0,1), ylim=c(0,1)) fit<-nls(proc~SSfpl(size, 1, 0, xmid, scal), start=list(xmid=0.2, scal=.1)) lines(seq(0,1,.01), predict(fit, newdata=data.frame(sito=seq(0,1,.01))), col=2) I tried

A lot of people have expressed interest in combining math features with Markdown, but I am not aware of any real developments from these requests. I was looking around and toying with [ASCIIMathPHP](http:// www.jcphysics.com/ASCIIMath/) and integrated it with MultiMarkdown and my xhtml2latex XSLT transforms. You can include math as an inline formula by using a markup similar to inline