[Cox proportional hazards regression][1] is a very popular, semi-parametric method for survival analysis.

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Propensity score in time-updated (counting process) Cox regression

Suppose I aim to examine if treatment A is better than treatment B. My dataset consists of 10,000 individuals with a total of 100,000 observations. Thus each individual is observed 10 times and his ...
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How to assess the proportional hazards assumption for a continous variable

I am having a problem with checking the assumptions for a continuous variable in a proportional hazards model. If a variable were a factor with many levels, then I could use the logrank test or check ...
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Comparing Cox Proportional Hazards Models (variable selection)

I am using a cox proportional hazards model to run a survival analysis in r on a number of non-nested, distinct covariates such as Age, Blood Type, Cancer, etc: ...
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Model assumptions and diagnostics for proportional hazard regression model with frailty in R

I am wondering are there any assumptions that must be met in the proportional hazard regression model with frailty? I remember that in regular proportional hazard model without frailty all variables ...
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Result of the summary of the proportional hazard model with frailty in R

I am trying to fit coxph a model with frailty with syntax below: ...
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Martingale residuals

I have read in a recent article that, with the use of Martingale residuals in a Cox regression analysis, one can better categorize a variable (different cut-offs). I have computed them using SPSS v19 ...
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How can I plot “intcox” interval cox proportional survival curve?

I'm doing survival analysis. I read intcox package manual but it doesn't provide R code for plotting survival curve. Anyone knows how to plot it? ...
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Create age and sexmatched pairs to balance Cox regression further (updated)

I analyze ethnic differences in risk of cardiovascular events (CVD) in a cohort study of patients with coronary heart disease. It is known that immigrants have higher risk of CVD and I intend to show ...
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Objective test for proportionality assumption in Cox Regression Model (SAS)?

I was trying to fit Cox Regression (aka Proportional Hazard) model on some cancer data (N=2288). I got the following output from SAS proc phreg: ...
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Logrank test for trend (proportional hazards)

How one can create a logrank test for trend and does it differ from normal logrank test? Any suggestions or literature? Maybe some R examples and functions?
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What’s wrong with this way of fitting time-dependent coefficients in a Cox regression?

I have a Cox proportional hazards model. Judging by Schoenfeld residual vs. time plots and corresponding tests for zero slope, there is clear violation of the PH assumption for several of the ...
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Outliers in proportional hazards model

How can one easily found an outlier in PH model and why are they so important? Can anybody give me some advice or suggest which R function may I use? Thanks for comments and help.
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Meaning of R's coxph output

I am getting below output from coxph function in R. ...
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rms package, getting zero Dxy in validation of cph model

I'm doing Cox proportional hazards analysis using Frank Harrell's rms package (4.2.0), with 3 strata. My model seems reasonably predictive on training data (Dxy=-0.537), but somehow in bootstrap ...
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Compare Cox with ANN

I am trying to compare Cox model with ANN by R but I have some problems. the result of package coxph is hazard but the result of package ...
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How to compare a Cox model with a neural network model [duplicate]

I am trying to compare a Cox model with ANN in R, but I have some problems: The result of package coxph is a hazard rate, but the result of package ...
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24 views

Survfit function in R to score a new dataset

I have built a cox proportional hazards model in the R survival package. I want to score new data set using this model. I thought the survfit function would doing this using survfit(original model, ...
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22 views

How to use coxph for prediction of event?

I fitted a cox model as: cfit <- coxph(Surv(tr$start, tr$end, tr$event1) ~ imp+sec + cluster(tr$compid)) Now i want to get the probability of event1 for the ...
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Does R square of Cox Regression tells the same thing as Linear Regression R square?

My R square from cox regression is about 0.02, Does it tell me that model is doing really bad? I used coxph in R.
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Combining two separate Cox PH models into one model?

I have two Cox proportional hazards models (in R), using same outcomes and predictors, one for $n_m$ males and one for $n_f$ females. Is it possible to combine them into one equivalent model over all ...
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Complete interpretation of Cox regression output in R

I need help with complete interpretation of this output(below). Can someone explain all (almost all) estimators in this output: what they mean and what is the substantive interpretation. In ...
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Running time dependent covariate model in R, getting warning

I am trying to fit this model, but it's giving a warning message I don't understand: ...
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Assistance with hazard ratios

I want to compare car accident deaths in two groups of people aged 18-24 (lets use this as the reference) and 24-30 after a certain law was changed using a Cox hazard model using SPSS version 22. I ...
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70 views

How to translate R to SQL for a Cox Proportional Hazards model?

I have built a cox model in R using the coxph function in the survival package, and now I need to replicate the model in SQL for scoring. From my understanding, the model has the form described on ...
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Applying Cox proportional hazards model to new data to get absolute risk (Framingham risk score)

I'm trying to apply one of the Framingham cardiovascular event risk scores to a new dataset in order to get absolute risk. D'Agostino 2013 "Cardiovascular Disease Risk Assessment: Insights from ...
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Addition of time before commencement of radiotherapy to Cox Model

I have a dataset from a clinical trial for which all cancer patients received radiotherapy, but at different times following surgical removal of their tumour. So more simply, I have a variable, time ...
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Can someone help me with the interpretation of this cox proportional hazards model and how to cross-validate it?

The question I'm asking is related to this question here and here. And I apologize for asking so many questions here, as I am thoroughly a stats novice and probably my MD thinking is clouding my ...
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spss macro for calculating nri and idi

I try to analyze if the addition of a biomarker to an established model could improve reclassification. Usually I calculate the NRI manually, but I was wondering if there is a macro that could do this ...
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Cox regression problem with time varying covariates

I was working on a cox regression problem and was refering to this link: http://support.sas.com/documentation/cdl/en/statug/63347/HTML/default/viewer.htm#statug_phreg_sect050.htm I have few ...
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Survival analysis in R with left-truncated data

I am doing a survival analysis in R with the survival package. I think I am working with left-truncated data, but I'm not entirely sure how to handle it. I have a ...
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Predicting conditional expected lifetime by Cox model in R

I'm using a Cox proportional hazards model, estimate the hazard rate for Levamisole relative to 5-FU, adjusting for Age and Sex. ...
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Cumulative Hazard Function where “status” is dependent on “time”

This question is in relation to a dataset I've previously discussed here. I'm trying to determine whether a treatment affects not only the number of visits a patient has to the doctor, but also how ...
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Negative Regression Coefficent (Cox Regression)

I'm doing a Cox regression analysis in order to verify the role of two variables on the prediction of disease conversion. Previously, I did a ROC analysis and a logistic regression. All these methods ...
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Testing residuals from a cox model with time dependent covariates

I'm doing survival analysis with time dependent covariates, using the counting process style. I already have a set of models and I want to test de residuals. I'm having trouble with the lack of ...
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Model speedup using weights in R

I need to run a cox-regression on a huge data set (millions) with only a few unique rows (hundreds) and regressing on categorical variable group. I could use just ...
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Evaluating Proportional Hazards with time-dependent variables

I'm doing survival analysis and using the survival package from R to do it. I have 7 variables, 5 of which are time-dependent (all except sexo and peso). Here is my model: ...
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Simulate censored data cox model

I would like to simulate interval-censored data in a Cox model. In the R package intcox I found the following code: ...
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How was this deviance formula for Cox Proportional Hazard derived?

The gbm package in R documents the following deviance formula for CoxPH models http://gradientboostedmodels.googlecode.com/git/gbm/inst/doc/gbm.pdf $-2 \sum w_i \delta_i (f(x_i) - \log(R_i / w_i)$, ...
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When is best to set the origin (time=0) point in a cox-propotional hazard model change analysis

I would like to know the relationship between change in a variable in the three months after a disease, and survival time. I have change in the variable in the first three months. But I am not sure ...
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Cox regression, survival, comparison with historic group, follow-up time

I have two groups of patients, treated at two time periods. I'm comparing survival. In the later group I have 3 years follow up time. In the early group I have of course access to longer follow up ...
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Cox regression with time varying covariates

I am looking for resources on Cox proportional hazards model with time varying covariates. I'm new to survival analysis so I'm looking for something not overly mathematical. I would also appreciate ...
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How to perform a constrast in R for a cox proportional hazards model

I have the following model fit: ...
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Cox regression to see if distribution of disease predicts survival

I'm working with clinical data from a few hundred patients. Every patient was measured at 6 different timepoints with regular intervals. Each patient is assessed on 3 different domains and given a ...
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Violation Proportionality Cox model - Repeat analysis?

I'm new to survival analysis, but I've been reading some papers and books and I got a nice model. However, one of the variables (Sit) does not met the proportionality assumption for the Cox model. ...
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R package to handle gene expression and proportional hazards model

I have survival data with RNA expression. A lot of the data is censored. Is there an R package that does a proportional hazards model where the number of covariates is much larger than the number of ...
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Error term interpretation in the Cox PH model

I am preparing a presentation on Survival Analysis models, with specific focus on the Cox model. I have been using such model (including its competing risks generalization) for some time now, but I ...
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Selection correction variable (non-randomly selected sample / bias) and Cox regression

I found an approach to calculate a selection correction variable for a Cox regression (Lee 1983. Generalized econometric models with selectivity. Econometrica 51: 507–512.): $$ λ = \phi \frac{ ...
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Inferring the statistical tests performed in a paper

I am in great need of help in order to infer the statistical hypothesis tests performed in Xanthelasmata, arcus corneae, and ischaemic vascular disease and death in general population: prospective ...
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143 views

p-value zero in hypothesis testing for survival curves

I have done survival analysis. I used Kaplan-Meir to do the survival analysis. Description of data: My data set is large and data table has close 120,000 records of survival information belong to 6 ...
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cox.zph says the standard deviation is zero

I need to compare my observed point vs random points that have been constrained to be relevant to that observation. In my case, I am looking at habitat selection along transects of animal movements. ...