similar to: cox.zph vs log-log survival plot

Dear experts, when I call the step function for a coxph model with n covariates and a dicotomous variable included as strata, the first term removed by step is always the strata variable. This is not what I want and then I do a manual step updating the model minus the least significant covariate and testing with anova, until I have minimized the model. Is there a package were this can be done? or

At work after updating to R 2.5 I get an error using epitab from package epitools, when at home (R 2.4) I get no error. Could someone help me? Thanks Pietro Bulian Servizio di Onco-Ematologia Clinico-Sperimentale I.R.C.C.S. Centro di Riferimento Oncologico Via Franco Gallini 2 33081 Aviano (PN) - Italy phone: +39 0434 659 412 fax: +39 0434 659 409 e-mail: pbulian at cro.it (at work)

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

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),

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

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

Hi, I''m trying to share internet on a LAN I''ve a linux router with SQUID (with ZPH support) + FAIRNAT The idea is: - fairness sharing internet - priorize interactive traffic - if a web object is on squid-cache (HIT), user can download it, with a rate = LAN rate I''ve: - Last Fairnat Script: www.metamorpher.de/fairnat/ - SQUID 2.5STABLE5 with ZPH patch

Hi, I am using the Survival package, more precisely the cox.zph function, to plot log(Hazard rate) over time. if I type plot(temp.zph[2]) then I get the plot I want. However, I want to change the label of the y axis that cox.zph prints. plot(temp.zph[2],xlab='Days', ylab='log hazard for Fast recovery cluster') then I get Error in plot.default(range(xx), yr, type =

Hi, I''ve used old ZPH patch under squid 2.4 Stable4 and it works great ! Now I want to patch squid 2.4 stable 5, with new patch, on http://www.it-academy.bg/zph/ I''ve patched and installed squid 2.5 stable 5 succefully, but I can''t get ZPH works. I''m trying with ... $TC class add dev $LANDEV parent 1: classid 1:7 htb rate 1Mbit $TC filter add dev $LANDEV

Hi, I used to patch my squid with ZPH patch on http://www.it-academy.bg/zph/ > The idea behind this patch is to allow classification > of packets generated from the squid cache engine towards > clients. > The classification is based on whether the content is > being served from cache (a cache HIT), or > is being retrieved from a remote server (a cache MISS). Very useful

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

> ... 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

Dear all, I use the Andersen plot to check for proportional hazards assumption for a factor (say x) in the Cox regression model and obtained a straight line that pass through the origin. However, the formal test done by the R-function cox.zph, which is based on the plot of Schonefeld residuals against time, indicates that proportional hazards assumption is violated. Further, a plot of the score

-- 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

Dear list: I am attempting to use what I thought would be a pretty straightforward practical application of Cox regression. I figure users of the survival package must have come across this problem before, so I would like to ask you how you dealt with it. I have set up an illustrative example and included it at the end of this post. I took a sample of 100 data points from each of two populations

> Dear All, > > I have built a survival cox-model, which includes a covariate * time interaction. (non-proportionality detected) > I am now wondering how could I most easily get survival predictions from my model. > > My model was specified: > coxph(formula = Surv(event_time_mod, event_indicator_mod) ~ Sex + > ageC + HHcat_alt + Main_Branch + Acute_seizure +

>Hello, I am hoping for assistance in regards to examining the contribution of stratified variables in a cox regression. A previous post by Terry Therneau noted that "That is the point of a strata; you are declaring a variable to NOT be proportional hazards, and thus there is no single "hazard ratio" that describes it". Given this purpose of stratification, in the

Hi, after standardizing my data by dividing each covariate by its mean, the hazard ratio of variables ranges btw ~ 0.5 and 3.55. when i test the PH assumption by cox.zph, rho ranges btw -0.4235863 and 0.359827. visualizing the PH assumption by plot, the plot of scaled schoefeld residuals against transformed time doesn't give a line with slope 0 for all covariates. note that there are 100