similar to: A model for possibly periodic data with varying amplitude [repost, much edited]

Hi dear R community, I have up to 12 measures of a protein for each of 6 patients, taken every two or three days. The pattern of the protein looks periodic, but the height of the peaks is highly variable. It's something like this: patient <- data.frame( day = c(1, 3, 5, 8, 10, 12, 15, 17, 19, 22, 24, 26), protein = c(5, 3, 10, 7, 2, 8, 25, 12, 7, 20, 10, 5) ) plot(patient$day,

Back on January 16, a message on R-help from Ravi Varadhan described a problem with gnls using weights=varPower(). The problem was that the fit failed with error Error in eval(expr, envir, enclos) : Object "." not found I can reliably get this error in version 2.0.1-patched 2004-12-09 on Windows XP and 2.0.1-Patched 2005-01-26 on Linux. The key feature of that example is that the

Dear R-helpers, I have time series data from 16 subjects and 2 treatment groups. The seasonal variation can be best described by two harmonics, I called the frequencies omega and omega2. I now want to test whether (1) the seasonal pattern differs between the treatments (some kind of overall test). If this is the case, (2) I want to conduct tests to find out whether the amplitude of the

Dear list, I apologies first for my English, hope you will understand well my question. I am working on 1/2 hour piezometric data, time unit is second. They present daily oscillation when using the spectrum() function. What I am really interested in, is to find the amplitude corresponding to this oscillation. I work with a college using Matlab, and although we apply the same methodology, our

Hi, I guess this is a final plea, and maybe this should go to R-help but here goes. I am writing a set of functions for calibration and prediction, and to calculate standard errors and intervals I need the variance function to be evaluated at new prediction points. So for instance fit<-gnls(Y~SSlogis(foo,Asym,xmid,scal),weights=varPower())

I did a fourier transform on a function in time domain to get the following functions in frequency domain (in latex): $Y_1[\omega] = \frac{1}{1-\phi_1 e^{-jw}}$ $Y_2[\omega] = \frac{1}{1-(\phi_1 + \phi_2)e^{-jw} +\phi_1\phi_2e^{-2jw}}$ How do I find the spectrum of this function for given $\phi_1$ and $\phi_2$ coefficients and in the discretization interval $w = [-\pi:.1*\pi: \pi]$? Then, how

I have been attempting to estimate the periodic contribution of an effect to some data but have not been able to fit a sine wave within R. It would be nice to start by being able to fit a sine wave with an amplitude and frequency. x<-seq(0,20,by=0.5) y<-2*sin(2*pi*.5*x) #amplitude =2, frequency=0.5 # This failed to converge r<-nls(y ~ A*sin(2*pi*F*x), start=list(A = 1, F = 1),

I'm getting some odd results computing log-likelihoods with gls using splines with increasing degrees of freedom -- the deviance *increases* substantially with increasing df. (Since spline models with increasing df aren't nested, it need not decline monotonically but I would expect it to have a decreasing trend!) I may just be confused, but I *think* the issue is somewhere within the

Hi: I have data from an assay in the form of two vectors, one is response and the other is a predictor. When I attempt to fit a 5 parameter logistic model with "nls", I get converged parameter estimates. I also get the same answers with "gnls" without specifying the "weights" argument. However, when I attempt to use the "gnls" function and try to

Dear list, What on earth is spec.pgram() normalized too? If you would like to skip my proof as to why it's not normed too the mean squared or sum squared amplitude of the discrete function a[], feel free too skip the rest of the message. If it is, but you know why it's not exact in spec.pgram() when it should be, skip the rest of this message. The issue I refer herein refers only too a

I am using the gnls procedure in nlme package to fit a nonlinear model as: nl.fit<-gnls(Y ~ b0*exp(b1/X), data = data1, params=list( b0~p1+I(p1^2)+p2+I(p2^2)+p3+I(p3^2)+p5+p6 b1~p8+p2+I(p2^2)+p3+p9+p10+p11), start = c(25,0,0,0,0,0,0,0,0,-8.6,0,0,0,0,0,0,0), weights=varPower(form =~ X)

Hi, I've been trying to work with the gnls() function in the "nlme" package. My decision to use gnls() was so that I could fit varPower and such to some of the data. However, in working with a small dataset, I've found that the results given by gnls() don't seem to make any sense and they differ substantially from those produced by nls(). I suspect that I am just

Here is another occurrence of wmTSA internal error. My time series is a short breathing cycle (2425-Cyle_9.txt). Since wmtsa functions that extract extrema seem to expect longer series than I have, I tried the folowing two tricks: 1) I prolong the 1-cycle series on both ends through duplicating the first value (on the left end( and the last value on the right end as any ties as the 1-cycle

Works perfectly. Thank you. -Hugh Rand -----Original Message----- From: Spencer Graves [mailto:spencer.graves at pdf.com] Sent: Sunday, January 15, 2006 6:41 PM To: Rand, Hugh Cc: 'r-help at lists.R-project.org' Subject: Re: [R] trouble with extraction/interpretation of variance structure para meters from a model built using gnls and varConstPower How about this: >

Using a more stable nonlinear modeling tool will also help, but key is to get the periodicity right. y=c(16.82, 16.72, 16.63, 16.47, 16.84, 16.25, 16.15, 16.83, 17.41, 17.67, 17.62, 17.81, 17.91, 17.85, 17.70, 17.67, 17.45, 17.58, 16.99, 17.10) t=c(7, 37, 58, 79, 96, 110, 114, 127, 146, 156, 161, 169, 176, 182, 190, 197, 209, 218, 232, 240) lidata <- data.frame(y=y, t=t) #I use the

Hi, I am not sure this is a bug but I can repeat it, The functions and data are below. I know this is nasty data, and it is very questionable whether a 4pl model is appropriate, but it is data fed to an automated tool and I would have hoped for an error. Does this repeat for anyone else? My details: > version _ platform i686-pc-linux-gnu

Doug, I have been attempting to learn a little bit about nlme without too much documentation except the online help. The Latex file in the nlme directory looks interesting but uses packages that I do not have so that I have not been able to read it. I have run the example from gnls to compare it with the results I get from my libraries (code below - I have not included output as it is rather

Thanks for the replies! My first thought was that the file had low levels (before he sent me the file), but that's definitely not the case with this file. There are many peaks that reach 0dBFS. He sent me the original wav this morning and I loaded it into Wave Editor on OS X. I dithered to 16 bit using MBIT+ (high/ultra setting) and saved the 16 bit file. I did nothing else (no

I want to compare the following two models in AIC (Treat, Spotter are categorial, p is pressure, Pain is continuous) PainW.lme<-lme(Pain~p+Treat*Spotter,data=saw,random=~p|Pat, weights=varPower(form=~Pain)) # AIC= -448 Pain.lme<-lme(Pain~p+Treat*Spotter,data=saw,random=~p|Pat) #AIC = -19.7 Note the huge differences in AIC, and the estimated power of 6. A plot of the residual

Hello, I am trying to design new variance structures by using fixed effects variables in combination with the VarPower function. That is, I would like to create and evaluate my own variance function in the data frame and then incorporate it into the model using varPower, with value=.5. As a start, I am trying to recreate the function of VarConstPower by introducing two new variables in the