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Questions tagged [cox-model]

Cox proportional hazards regression is a semi-parametric method for survival analysis. No distributional form needs to be assumed, only that the effect of one-unit increase in a covariate is a constant multiple.

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Compare fit Cox models with clusters in R

I would like to compare the model fits of Cox proportional-hazards models with a likelihood-ratio test (or equivalent). This usually works by comparing the fit with the ...
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Survival Analysis: event & censor coding

Simple query I suspect. I've been running a cox regression in R and noticed that my time-to event and time-to-censoring models produce identical output. Is that what I should expect? That is, does it ...
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Survival analysis for fixed time period licencing

I need to predict attrition of customers who use product that has fixed time period (1 year) licence. I have monthly feature usage data, for example the product has 5 features f1, f2, f3, f4 and f5, I ...
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Bias in parameter estimates for Cox proportional hazard model when covariates are collinear

For linear regression, if $y$ actually depends on two positively correlated covariates $x_1$ and $x_2$ (we can call it the true model), and if we only include one covariate, say $x_1$, in the ...
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R package `survival`: the estimated parameters are off

I simulated some survival data and used the R package survival's function coxph to estimate the parameters, but they are ...
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Poisson Regression vs. Exponential_Weibull vs. Cox Regression vs. Negative Binomial

Problem: I would like to predict the number of days a student continues with school using student and school level covariates (no censor data). Data includes the number of days that the student ...
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Interpreting this KM Curve

I would like someone experienced to look at my KM curve. I have categorized a continuous clinical variable into 2 groups based on its median. The Log rank test is significant (p=0.0052). I have then ...
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Cox's Proportional Hazard coefficients clarification

I'd like a clarification about the Cox proportional hazard coefficients reported on this page. For example, doesn't the hazard ratio (HR) for gender in that ...
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What are criteria to select the variables to include in a multiple Cox regression model

I have a group over about 500 subjects and want to perform a cox-regression to find predictors of an event taking into account the time to event. I have 12 potential predicting variables that I want ...
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Cox regression - unknowns within covariates

I have run a model for duration in treatment. Records have either exited treatment or are still in treatment. If exited, the number of days is known. If still in treatment, the number of days in ...
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Real 1 dimensional non-binary data where Cox Proportional hazards model fails

I am learning about the Cox Proportional Hazards model and understood that it is very flexible, even when the assumption of proportional hazards is not met, e.g. for additive hazards. But say we have ...
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Cox Regression Specifics: Standardizing, Log Transforming

In the statistical analysis of this paper I have some questions regarding their approach. https://academic.oup.com/ndt/article/33/6/1001/3978817 “Variables with non-normal distributions were either ...
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Shared Frailty Assumptions

Do we need to check the proportional hazards assumption when running a shared frailty model for clustered data?
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Predict hazard relative to a specific sample

I want to predict the hazard ratio and 95% confidence intervals relative to a specific sample rather than the population mean: ...
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Cross-validation of (Cox) survival model with very high censoring rate

I am currently working on survival analysis of data with very high censoring rate (~99%), and the number of events is only about 500, using R. I would like to ask in such case, whether the validate() ...
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Question regarding the Supervised Principal Components method

I'm going over Bair's and Tibshirani's Supervised PC method and looking at their R package tutorial here. In their paper, in the section titled "A Breast Cancer Example," it seems they find the most ...
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Cox time-dependent coefficient continues to violate the PH assumption

After determining that my Cox model with a particular covariate (drug) was violating the proportional hazard assumption, I took steps to incorporate a time-dependent continuous coefficient given how I ...
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Clarification for LASSO based Cox model using glmnet

I am trying to find a variable signature associated with a characteristic. Particularly I am looking to get a prognostic model from multi-variable data for gene expression. I have the "Time (survival ...
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Continuous vs Categorical covariate of interest in Cox Regression

I will use aliases throughout to explain my results in brief and a few questions that have propped up in the process. Suppose I'm interested in the association of baseline measurement of blood ...
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Cox proportional hazards model with interaction terms

I am looking at a survival analysis using Cox PH models. I am interested in the effect of a continuous variable V1 on survival. I want to look at interaction terms with my model. I believe variable ...
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What survival model is suitable for not comparing groups?

I initially used Cox PH model for my data for different subgroups of my population, however I do not want to make any comparisons between groups, rather i need to describe the time to event for each ...
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Equivalent of Kaplan Meier for an unbounded number of sets

I have used Kaplan-Meier method several times before when I compared how group $A$ survived compared to group $B$ through a period of (say) 5 years. Now I face a somewhat different scenario: I have ...
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propensity score matching by disease and cox PH regression.. am I right?

Normally I understood propensity score matching is the way to match the treated group and untreated group. But I noticed some studies that used propensity score matching to match disease and non-...
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Competing Risks Likelihood in each State

I have a competing risks model where every observation starts in state 0 and ends up in either state 1 or state 2. I have the following cumulative hazard functions for each transition to state 1 and ...
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Error for Validation of Cox model with extern dataset using rms val.surv by Frank Harrell [closed]

i developed a cox model for cancer overall survival with the rms-package. I use a with 765 observations (194 intern, 571 extern). So I divided in two datasets: Training and Validation I get a correct ...
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Interpreting glmnet cox coefficients

There have been similar questions regarding interpretation of glmnet results. However this is more specific to the cox part of the package. I am trying to create a prognostic score for cancer ...
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Lasso cox regression with bootstrap

I'm looking at building a nomogram for cancer prognosis based on 20 variables. This will be derived from a cox ph model. In the past I used poor methodology including dichotomization and stepwise ...
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Problem with reference category after survSplit in Cox regression

I have two covariates in a survival data, Acet with four factor and Age as a continuous variable. I want category AAA to be the reference in the covariate Acet. Normal Cox regression is fine: ...
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Large discrepancy between complete-cases and imputed data

I would like to conduct a survival analysis using a dataset with approximately 12,000 participants (1100 events). However, complete data are available for only 9500 participants (820 events). I have ...
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Proportional hazards assumption for cox regression - global test or graphical assessment

I have run a cox regression with only a treatment in mind so far and have then tested the proportional hazards assumption along with a graphical assessment using the log-log survival plot. My global ...
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Analyzing uncensored time-to-event data with no risk of events after a certain period

I'm trying to investigate several independents on a dataset with time-to-event data for a treatment. I'm measuring time-to-treatment effect (where treatment effect is a binary parameter). Treatment ...
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How can I compare parametric and semiparametric survival models?

On a given dataset, I am running a semiprametric Cox proportional hazards model, together with a series of parametric models (Weibul, gamma, lognormal, exponential, etc.). How can I know which is ...
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Strategic interaction (dependencies) between observations in Cox regression?

I want to study the survival times of subjects with Cox regression, but I suspect there may be strategic interaction between the subjects. How can I account for such dependencies in a Cox model? For ...
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Help with plotting coxme data

I've run a mixed effects cox model using coxme in R. I can find code online regarding how to plot regular cox proportional hazards data but nothing about coxme. I am receiving error messages if I try ...
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Cox hazard Model: HR of 1 variable greater than 1 in simple regression becomes smaller than 1 in a multiple regression

I'm performing a simple and multiple Cox regression. I have 1 dependent variable $y$ and 10 independent variables: $$X = x_1, x_2, x_3, x_4, x_5, x_6, x_7, x_8, x_9, x_{10}$$ A particularity of the ...
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Prediction problem in normal regression models and survival analysis cox PH [closed]

I am trying to predict the duration it takes for gas pipes to leak. I used 15 features which the most important one is “pipe installation year”. The latest leak data that I have is for a leak that ...
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Underlying Poisson Distribution in Cox Regression with censoring

My question stems from this post: Does Cox Regression have an underlying Poisson distribution? Cox regression with no censoring can be interpreted as Poisson regression. Can we interpret Cox ...
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How can I change the 'baseline hazard function' from its default?

I have implemented a gap time-conditional (aka PWP) recurrent Cox regression model in R. However, rather then baseline hazard function (delta_0(t)) acting as a constant, I would like to incorporate a ...
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SPSS cox proportional hazard model adjusting for age

I'm using SPSS to run cox proportional hazard model. I've five different groups and I need unadjusted and adjusted (for age) HR for all of them separately. My first group is a reference group. I've ...
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Predicting whether house is sold: regression or classification

I am new to machine learning (I am currently following the Udemy course machine learning from A-Z). Basically, I would like to reproduce the following analysis (https://www.datasciencecentral.com/...
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Cox Model with time-varying covariates in mlr

I am using the mlr package in R to perform survival analysis. mlr includes the Cox Proportional Hazards Model (function coxph from library survival) as one of its integrated learners. As I understand ...
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Minimum sample size to trust univariate cox regression

I have performed a univariate Cox proportional hazards regression for an admittedly miniscule group of 25 samples, and consequently received a certain p-value (significant) and an associated ...
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Survival analysis of identical items in lifelines

I am doing survival analysis of hardware (more precisely, hard disk drives) and wanna predict HDD expected lifetime from its specs. I have a dataset of drives, where for each drive its lifetime in the ...
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How to model change in independent variable for Cox Proportional Hazards Model?

I'm interested in calculating a time to event model (Cox Proportional Hazards Model) and one of my independent variables has multiple measurements. I'm planning on using a time varying covariate for ...
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Interpretation of Cox Hazard Model with quadratic term

I am having trouble finding information on how to interpret coxph model hazard ratios with a quadratic term. Some of my variables are continuous count data, whereas others are continuous percentages. ...
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Cox regression with two events

We have a status variable with three events: 0) Censored 1) Relapse 2) Death We want to examine if two different types of medicine have a different risk on either death or relapse. How can we compare ...
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3answers
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Extremely huge Hazard Ratios from Cox regression

We made a cox regression and ended up with huge HR for some of our variables. One of them (which was an interaction) gave us a HR=2747,093. Our dataset consists of only 74 observations. What is wrong?
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Using Mean Cumulative Function (Nelson-Aalen) to assess drug efficacy

I have a large medical retrospective longitudinal dataset of electronic health records. An individual is identified by an ID. A medical event or drug prescription event is identified using a code and ...
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1answer
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How to control for severe medical cases using survival analysis and Cox regression?

I have a longitudinal medical record dataset. My cohort is made up of patients with a particular disease. There are no members of this cohort without this disease. Disease indications are denoted by a ...
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Time dependent variable in survival analysis using Cox regression

Trying to determine how to analyse a time dependent variable (rainfall) in a survival analysis. Two rows of example data for animal A and animal B as below: Each value next to the animal represents ...