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

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Get survival rates from a cox regression in R

I am fairly new to survival analysis and am playing around in R. I have a fairly simple cox model ...
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Univariate cox regression hazard ratio in SPSS

I'm currently doing some analysis for a retrospective cohort study of biomarkers in cancer patients. I've noticed that some papers have utilized univariate cox regression analysis to generate a hazard ...
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Parameter estimates from extended cox model using the coxph() function from the survival package in R

I want to understand how the parameters from a Cox Model using the coxph() function from the survival package in R are estimated. I am following a book by Rizopoulos [1]. In the book the partial log ...
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covariate-adjusted analysis for time to event endpoint in a cross over design RCT

I have a time to event endpoint in a 2x2 crossover RCT which I would like to analyse with a regression model to adjust for covariate effects. I am supposing I cannot fit a Cox proportional Hazards ...
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Risk ratios in a Cox hazard model

I'm reading a paper which gives "Risk ratios from Cox hazard models with time-varying covariates". Time-varying covariates just means that, for example if $X_i$ is a covariate for person $i$ then it ...
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55 views

Post-hoc power size calculation

I have, probably, a simple problem. I've finished analysing the results of an observational prospective study conducted in our unit. In this study I evaluated if a specific biomarker is independently ...
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How to interpret the R output of anova.coxph

The likelihood ratio chi^2 test is the gold standard for comparing nested Cox models. However I am not sure how to interpret the R output. ...
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Time varying coefficient in cox model

I have a model for survival after an injury that is borderline passing the Schoenfeld test for the proportional hazards assumption (cox.zph() in R). However, ...
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How to do Cox regression if we have a variable which violates an assumption?

Is there a better way than stratification to do Cox regression for two variables, one qualitative and other quantitative, the qualitative (and more important one) violates an assumption of Cox ...
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Cox Regression: Testing for effect in subgroup

I'm using a cox proportional hazard model in R to see if a treatment variable (treatment or placebo) has effect on the survivaltime of patients. I intend to test this for each of my grouping variables ...
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Simple Cox-related question regarding the LR test

I'm writing the Results section of a paper: If the LR-test for a Cox proportional hazards model is not significant, but one of the predictors is significant, does one (usually) report the covariate's ...
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Cox Regression Model

I have been simulating survival times, status and explanatory variables to apply in a Cox model, for a cohort of 10000 people. In this case, all the covariates were continuous and generated using a ...
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Predict Kaplan-Meier Curve from Hazard Ratios

For illustration purposes I want to plot some potential hazard ratios, based on a known proportional hazard model. For example, plot the known curve, then plot what the curve may look like with HR's ...
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Relative Risk with Log-rank test

I always associated/used log-rank test to evaluate Hazard Ratios. However, a well-known professor is using/presenting results of log-rank test for Relative Risk and Risk Ratio. Can anyone explain ...
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How to fit cox ph model in R to pre aggregated data

What I mean is suppose instead of individual observations one has only grouped data like this: Month,Age,Height,NoOfObseravtions,DeathRate 1,20-25,5.5-6.0,100,1% 1,20-25,5.5-6.0,150,1.20% ...
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Extracting univariate regression for multiple predictors into one table

I am doing univariate Cox regression for multiple variables: ...
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Cox-Proportional hazards model with panel (longitude ) data

I am working with panel data with incomplete case: and the goal is to predict the probability of 1 at each time for each case. I am trying to use the cox-ph model for this analysis because like ...
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How to visualize logistic and Cox proportional hazards models

One of the examiners of my thesis wants me to show a diagram of the logistic regression and Cox regression models complete with variables. Anyone with an idea of what I should do?
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Does fitting Cox-model with strata and strata-covariate interaction differ from fitting two Cox models?

In Regression Modeling Strategies by Harell there is a section (S. 19.1.7) discussing Cox models including an interaction between a covariate whose main effect on survival we want to estimate as well ...
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Temporal features in survival analysis

I'm modeling customer churn, experimenting with both Aalen Additive and Cox Proportional Hazards models, using the lifelines package in Python. If this were a more ...
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What is the right way of computing baseline hazard rate

What is the right way of computing baseline hazard rate? To my understanding hazard rate at time t is simply #events / #AtRisk ...
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Check hazard proportional assuption in a large coxph

I would like to check hazard proportional assuption in a large coxph. Usually I check it with cox.zph but with large coxph my p-value are very small whereas the log(-log(S(t)) curves are almost ...
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Interpretation of non-significant parameters in significant Cox-model as prognostic factors

I want to analyze predictive factors for patient survival after surgery. I have variables that are based on investigations at the time of the surgery, known predictive factors (age, KPS) and data on ...
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P-value from proportional hazards regression object [closed]

I'm running some proportional hazards regression models using the survival package in r and would like to know how I can access ...
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Dummy variables and intercept in Cox regression

I am working with the Cox Proportional Hazards model. Where the covariates include 2 categorical variables. Assume each category has 3 levels, so I model these in terms of dummy variables. Category ...
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Comparing survival times in small samples for two groups

I am working on a dataset of big cats. 18 cats have a particular antigen and the rest (58) do not. We have contact times for when blood samples were taken - so when the cats were identified as having ...
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Interpretation of the hazard ratio in a spline model on continuous exposures

I am having trouble interpreting the output from a Cox proportion hazard model with a spline term on a continuous exposure. In the below example (pseudo-code from ...
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how to interpret log transformed variables in survival analysis?

Suppose I have the following models: fit1 <- coxph(Surv(y,cov)~x,data=records) and ...
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Survival analysis coxph using ridge regression with 2000 variables => “Penalty terms cannot be in an interaction”

I'm doing a survival analysis using coxph function (package survival). I'm using a ridge regression model included 2000 variables but I have a type of error message "...
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Different “end of study” times for different cohorts - Cox PH model in survival analysis

I have a dataset with 4 cohorts of about the same size (~700 people each). I'm trying to apply a Cox PH model using the time needed to pass a very difficult exam as my "time" variable. The cohorts ...
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Proportionality assumption test (SAS) for categorical predictors

For Cox regression with all categorical predictors, I want to model time-dependent covariates (time*cov in Proc PHREG) to ...
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1answer
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Can you use event history analysis if your sample was selected on the dependent variable?

I have a dataset that includes a random sample of individuals who are currently in a relationship in the United States. I also have data on the date that they met their partner and the date that they ...
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ROC and post estimation COX Harrell's C using your dataset

I have built a predictive model using a combination of logistic and cox regression models. I did it using a dataset of about 5000 records. I would like to calculate the AUC and the Harrell's post ...
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What are valid ways of analysing predictors for a response variable that changes with time?

I have a cohort of similar patients who are likely to get a certain disease over time. I am trying to find out how some continuous health markers (e.g. weight) at time 0 are related to their disease ...
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How does left truncation affect the calculation of the logrank statistic for comparing two survival curves?

I'm currently doing survival analysis in R with left truncated data and am having trouble understanding how truncation affects the shape of a survival curve, and the results of a logrank test which ...
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Cox PH Modelling: How important are ties to the end result?

I am working on create a survival model using Cox PH, but am concerned with the limitation of the continuous time requirement. In my dataset there are often ties. For example, out of 35000 records, ...
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Are there any possibilities to check model assumptions or any diagnostic for the proportional hazards model with correlated times?

As far as I know, regular proportional hazards model have assumptions that times have to be independent, hazards for each variables should be proportional and there should be noninformative censoring. ...
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Can proportional hazard regression predict the S(t) of subjects?

In my understanding, cox PH model can only give estimates of coeffs of regressors and then interpretations can be drawn. Since it does not assume a base hazard function, it cannot give an estimated ...
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Some doubts about survival analysis

I'm struggling to perform a correct and unbiased survival analysis, but I have some doubts. Data I observe a population of posts on a blog within a temporal window $[T_{0}, T_{final}]$. Each post ...
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Modelling proportional hazards in Cox Model using coxph in R

Assume I have a heterogeneous sample with two categorical variables A and B, each with 2 levels. Now I want to measure the effect of these on the survival function. So we assume proportional hazard, ...
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PH assumption: categorical variable (1 category does not interact with time)

After checking the PH assumption in STATA I found one variable (4 categories, 1=ref.) to interact with time (using 'tvc'). The 3th and 4th category had p-values <0.05. However, the 2nd category did ...
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how can I save the survival probability that used to calculate NRI for an indiviual?

I am trying to save the survival probability that used to calculate NRI (i.e. in the survIDINRI package) for an individual. and I wanted to use these probabilities to further analyse what kind of ...
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Cox model on bank customers

I am setting up a Cox model, to model the probability that new customers leave the bank . I had a nice set up, with plenty of significant explanatory variables, until the result of one categorical ...
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coxph R Squared Interpretation in R [duplicate]

A classmate and I have been looking over some stats regarding a study looking at the (lets call it) survival rate of an item of food. He ran his analysis using coxph to generate a model to compare the ...
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Cox/ Binomial Regression: How to reconcile Non-significant model with significant IVs

I'm been performing some survival and regression analyses corresponding to an event of interest being death or a certain surgical procedure, namely a shunt revision for pediatric neuro-surgical ...
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Setting up dataset for Cox regression with time-dependent variables

I posed a question about how to set up the code for this question here (SAS/proc phreg code) and @Fomite suggested that I pose a separate question about whether my data are set up correctly. ...
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SAS/proc phreg code

Background: I'm studying people seeking help. Participants described contacts with between 1 and 3 "responders" (e.g., friends, the police) in order- for example, a participant could have contacted ...
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Interpreting Cox & Binomial Regression: non-significant Chi-Square values w/ significant wald statistics

Scenario A: In Cox regression, the chi square analysis of the -2 log likelihood (or the omnibus in binomial) is not significant, but some of the values of the Wald statistic corresponding to some of ...
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How to interpret the overall model output of a Cox model?

I am running Cox regression analysis. I have read FOX's manual and I understand how to interpret the output of each predictor. But I am not sure how I should be interpreting the overall model output, ...