similar to: cox PH

This is a question about the use of the Cox proportional hazards model to analyze event histories. I am looking at the responses of sympathetic nervous system activity to a stimulus. The activity I observe is a burst that can only occur once per heart beat cycle (e.g., a binary count). Typically bursts occur in 60-80% of the heart cycles * sensory stimuli can modify these burst probabilities.

Hello, I am hoping for some advice regarding warning/error messages I received when running a Cox regression # message 1 - obtained while creating a plot of residuals > plot (NV.zph, main = "groupNUSM - UNFIT", var= 'groupNUSM') Warning messages: 1: In approx(xx, xtime, seq(min(xx), max(xx), length.out = 17)[2 * : collapsing to unique 'x' values 2: In

Hi all, I was trying to test the assumption of proportional hazards assumption, I used the cox.zph function >cox.zph(coxfit6) Results are: rho chisq p x1 -0.0396 1.397 2.37e-01 x2 0.1107 9.715 1.83e-03 x3 -0.0885 7.743 5.39e-03 x4 0.0366 1.092 2.96e-01 x5 0.0242 0.455 5.00e-01 GLOBAL

Hello, Excuse me for a more methodological than technical question. I'm developing a Cox model with 10 covariates. One of them is age (named "eta"). I've checked proportionality with cox.zph with age continuous: > cox.zph(coxph(Surv(TTP,CENSOTTP)~eta)) rho chisq p eta -0.0154 0.0225 0.88 and categorical (eta<60): >

It seems that there is a problem in displaying subtitle in general, independently from multi-plot display. when I do plot (c(1,2,3), c(9,8,7), type = "l") title(main = "Main title", sub ="Sub title",cex.main=2, cex.sub = 2) subtitle doesn't get displayed > --- On Sat, 11/21/09, David Winsemius <dwinsemius at comcast.net> > wrote: >

Hello, I got error message when applying the plot function to the cox.zph object to create the Schoenfeld residual plots. > plot(zph.revasFit[1]) Error in plot.window(xlim, ylim, log, asp, ...) : need finite 'ylim' values In addition: Warning messages: 1: NaNs produced in: sqrt(x$var[i, i] * seval) 2: no non-missing arguments to min; returning Inf in: min(x) 3: no

Hi, I get a warning message when I plot cox.zph objects with the transform km and rank, but not with id and log with the same data set. Here's the command: example is a coxph object rk <- cox.zph(example, transform='rank') rk plot(rk) and here's the warning message: Warning messages: 1: suppression des ex-aequos de 'x' in: approx(xx, xtime, seq(min(xx), max(xx),

> ... interactions between covariables and time. A model such as "coxph(Surv(ptime, pstat) ~ age + age*ptime, ...." is invalid -- it is not at all what you think. If cph flags this as an error that is a good thing: I should probably add the same message to coxph. > Is is somewhat sensible to use cox.zph() to investigate which variables need time interaction... The cox.zph

To enhance my understanding, and that of my students, I have a question about cox.zph in the survival package. If I have correctly gleaned the high-level point from the 1994 Biometrika paper of Grambsch and Therneau, it looks to me like cox.zph provides a mechanism to test for a simple trend in plots of a function of time, g(t) versus the scaled schoenfeld residuals and it also provides some

You report an error message: > plot(zph.revasFit[1]) Error in plot.window(xlim, ylim, log, asp, ...) : need finite 'ylim' values I have never seen this error before, and I cannot guess what causes it. You need to provide more information, and likely a small data set that produces the problem. Perhaps you have an x variable that is a constant? Terry Therneau

Hi, I would like to ask how can I do the problem as follows by R. Thank you very much. Q: Create a list of twenty distinct first names, ten male and ten female, and store them into an array. Write a routine for selecting a simple random sample of five names and counts the number of male and female names in the sample when the sample is drawn : (a) with replacement (b) without

Dear R-users, I am sorry if this is obvious. I am testing the proportional hazard assumptions using cox.zph. If i am not wrong, a g(t) function must be assumed. Four possibilities available in R are "km","identity" and "rank". may i know what functions of time are these transformation assuming? Thanks a lot in advance for your wisdom. kind regards, sing yee ling

-- begin included message --- I am hoping for some advice regarding obtaining the values for the hazard function in a cox regression that I have undertaken. I have a model in the following form, analysed with the package survival (v. 2.34-1) and a log-log plot obtained using Design (v. 2.1-2). For two variables, the lines in the survival curves crossed. The statistician I been obtaining

if nobody knows the answer to my question on time-dependent ROC (see below), does any body know how TP and FP are related to classes and samples (orders) in non-time dependent ROC? Any reference? Thanks --- On Tue, 11/3/09, carol white <wht_crl at yahoo.com> wrote: > From: carol white <wht_crl at yahoo.com> > Subject: ROC > To: r-help at stat.math.ethz.ch > Date:

Hi, What is the function for inverse normal transformation? Thanks, Carol [[alternative HTML version deleted]]

Hi, How to plot the same types of graphics on the same R graphic device? Suppose that we want to plot a vector y against x (using plot for instance). How is it possible to plot y against x for different values of these two vectors on the same device so that the plots could be compared? Cheers, Carol [[alternative HTML version deleted]]

Hi, I got problem in using title function to create a title for multiple plots presented together by par. As can be seen in the attached file, the title is displayed truncated and the subtitle doesn't get displayed. Here is the code: par(mfrow = c(1,2)) plot(c(1,2,3), c(9,8,7)) plot(c(1,2,3), c(9,8,7)) title(main = "Main title", sub ="Sub title",outer = TRUE,

Hello, How is it possible to sort dates in R? Cheers, Carol

Dear All, I tried to invoke plot for a matrix of?196475 x2 dimension. I loaded the data with read.table. On one dimension, there are strings (names) and on the other dimension, the floats between 0 and 1. When I invoked plot by setting x to names and y to floats and ylim = c(0,1), I got the following error message: Error in rep.int(boxwex, n) : negative length vectors are not allowed Does it

Hello, It might be an easy question but if you have many variables to fit in the lm function, how do you take all without specifying var1+var2+...+var2100 in the terms parameter in response ~ terms? Cheers, Carol