search for: gastric

Hi Guys, I have this part of a program: library(survival) Gastric <- cbind.data.frame(Gp=c(rep(1,45),rep(0,45)), ### 2nd gp 0 time=c(1,63,105,129,182,216,250,262,301,301,342,354,356,358, 380,383, 383,388,394,408,460,489,499,523,524,535,562,569,675,676, 748,778,786,797,955,968,1000,1245,1271,1420,1551,1694,2363,2754,2950, 17,42,44,48,60,72,74,9...

...which was not previously received with the same code. I recently updated all my packages. It does not seem to be a peculiarity of my data as I receive the error using data available in R. A plot is produced but I am uncertain regarding the error message. > library(surv2sample) > data(gastric) > fit <- survfit(Surv(time, event) ~ treatment, data = gastric) Error in get(x, envir = ns, inherits = FALSE) : variable "survfit.km" was not found > #Default plot: > plot(fit) regards Bob Green

I have a table like the following. I want to fit Cm to Vm like this: Cm ~ Cl+Q1*b1*38.67*exp(-b1*(Vm-Vp1)*0.03867)/(1+exp(-b1*(Vm-Vp1)*0.03867))^2+Q2*b2*38.67*exp(-b2*(Vm-Vp2)*0.03867)/(1+exp(-b2*(Vm-Vp2)*0.03867))^2 I use nls, with start=list(Q1=2e-3, b1=1, Vp1=-25, Q2=3e-3, b2=1, Vp2=200). But I always get 'singlular gradient' error like this. But in SigmaPlot I can get the result. How

I'm having problems getting nls to agree that convergence has occurred in a toy problem. nls.out never gets defined when there is an error in nls. Reaching the maximum number of iterations is alway an error, so nls.out never gets defined when the maximum number of iterations is reched. >From ?nls.control: tol: A positive numeric value specifying the tolerance level for the

Dear All, I am doing experiments in live plant tissue using a laser confocal microscope. The method is called "fluorescence recovery after photo-bleaching" (FRAP) and here follows a short summary: 1. Record/ measure fluorescence intensity in a defined, round region of interest (ROI, in this case a small spot) to determine the initial intensity value before the bleaching. This