Questions tagged [survival]

Survival analysis models time to event data, typically time to death or failure time. Censored data are a common problem for survival analyses.

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Using auroc score and brier score to evaluate the performance of fully parametric survival models

I developed both semi parametric and fully parametric multi state survival models in R and wondering how i can compare their performance. I saw similar question asked here and the answer was to use ...
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Understanding variable classification decisions in XLStat's tutorial for Cox PH

I was going over XLStat's tutorial for Cox PH and while I'm fine most of the process, I find it hard to understand why have they chosen treatment group (rx) and ECOG performance status (ecog.ps) as ...
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Hazard crossing for survival curve

I am very confused because people say the following pic is showing hazard crossing, but the y_aixs is actually not h(t), it is s(x) the survival probability, then how do you conclude they are showing ...
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Exponential with Long Tail?

I am modeling the time until the next visit to the doctor of patients using a survival model assuming exponential distribution for the dependent variable. I have coded the dependent variable (time ...
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Appropriate way to report cox proportional hazards model

I have a dataset of 150 patients and 10 variables. I wanted to run a survival analysis, so I did the following: Univariate test (log-rank for my categorical variables, univariate Cox proportional ...
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Case-Cohort analysis in R

I am attempting to conduct a Case-Cohort analysis with Cox's Proportional Hazards Model. The data set looks similar to the one below: ...
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Defining an applicable score index for patient survival prediction

Say I want to devise a score index for predicting patient overall survival (OS) based on a handful of co-variates, what would be the best way to do it? Briefly, I have performed a Cox regression ...
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23 views

Hazard rate from Weibull vs. cumulative hazard plot does not match

) My problem is that I have HR for a factor named "Selvrisiko" and I get the output estimates (HR) (Upper bound) (Lower bound) as: but when I plot (Kaplan - Meier) cumulative hazard for the ...
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Predicting the loan default probability for next t intervals by predictSurvProb()

I have a loan dataset that contains details of customers for different loan types. Every category of loan have different tenure(starting from 6Months to 60Months) We are defining "Good" or "Bad" to a ...
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Fitting a Linear Mixed Effects Model

Suppose I have data on 4 units, $X_i(t_{ij})$, for $i= 1,2,3,4$ and $j = 1,\dots,10$. That is, I have 10 observations for each unit. The observations for unit $i$ were recorded at times $t_{i,1}, \...
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Is there a way to compute the Kaplan-Meier mean for left censored data using lifelines in python? [closed]

I am using the lifelines python package to fit Kaplan-Meirer models to left-censored environmental data. I am computing the mean using lifelines.utils.restricted_mean_survival_time(m,t) where m is ...
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Check if PH or AFT model should be fit

It is unclear to me when it is appropriate to fit an accelerated failure time (AFT) model rather than a proportional hazard (PH) model. I've tried googling and it appears as though PH models are ...
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Predictive performance of joint models versus standard survival models

I am trying to show that predictions based on repeated measures of markers (using joint modelling of repeated markers and time to event models: JMbayes package) are better than those based on only one ...
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Why is stepAIC making preference for more variables and reaching infinity for AFT survival model?

I have about 25 regressors where I applied an AFT Weibull model to consider the 25 covariates in the dataset. I then used the stepAIC approach with backward, forward and exhaustive search where it ...
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How to conduct stratified Cox regression with Lasso regularization and k-fold cross validation in glmnet in R?

I have been conducting Cox PH survival analysis and I am new to this. I am following the steps below: Create surv object and predictor model matrix for variables I am interested in. Since my data is ...
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What is the relationship between the Harrel's C and the AUC?

I model survival outcomes using a Cox proportional hazards model and want to evaluate model fit. Harrel's concordance index C is defined as the proportion of observations that the model can order ...
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Survival analysis: Frailty vs Sandwich variance estimators

Question Can someone answer (in as non-technical terms as possible) whether or not frailty models and robust sandwich variance estimators are trying to solve the same problem in different contexts? ...
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Joint models with time to progression

Consider a RCT (Randomized Controlled Trial) which aims at assessing the efficacy of a drug in patients suffering from a given cancer. In this trial, $p$ individuals are observed at several time ...
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Survival analysis cox model and accelerated failure time (AFT) variable selection

I'm reading a paper about survival analysis. After doing the univariate analysis, the paper only put covariates which have significant results in the univariate analysis into the multivairate ...
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1answer
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Is it possible to compare survival curves from different models (Cox and Fine-Gray)? Ideally in R

I would like to perform a time to event analysis on some biological example with animals. The event of interest is a terminal event X. But the animal may die from other reason before it happens. So I ...
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Bivariate Kaplan-Meier Estimator

Are there any builtin functions or packages in R which calculate the Kaplan-Meier estimator in two dimensions? For example, consider observed quadruples of failure/censoring time pairs and failure/...
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How make distinct predictions for every observation using survreg for AFT models?

I have a life dataset where I have a few machines tested using the same parameter settings but results in different survival days. As an example below: ...
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Modeling entering a lifelong treatment at different ages

Let's say I'm working on a pill that extends (or reduces, if I'm a bad scientist) the life of anyone taking it. It only works on individuals at least 70 years old, but they may start taking the pill ...
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Left-Truncated Right-Censored Cox Proportional Hazard Regression

If I have a left-truncated (remove everyone who has disease at baseline) and right-censored (1 if the person develops disease, 0 else). Time to event = min(age censored, age at disease diagnosis) ...
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Representation of cubic-linear spline in mgcv::gam

I have a dataset of empirical hazard rates which I would like to model to produce a reasonable forecast of the survival rate. I'd like to use a cubic-linear spline to fit the logit-transformed hazards ...
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How to approach feature selection for AFT survival models in R?

I can't seem to find much guidance on how to select features when implementing survival models. I have tried using the leaps package but I realised since I am dealing with censored observations, I may ...
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Kaplan Meier Retirement Analysis

Scenario: I am trying to find the probability someone retires at a specific age using the survival probability package in R. The way I am trying to frame this study is by only looking at individuals ...
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Survival Analysis/Customer Attrition Model for Balances

I’m looking to model balance, meaning dollars, decay(attrition). In brief, I have time series customer data, which is aggregated to get customer’s balances for a specific product. Over time, the ...
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R coxph vs. coxme: Vastly different Coefficients of Determination

Comparing comparably defined models in R's coxph() and coxme() I experienced hugely different results when calculation the Coefficient of Determination using MuMIns r.squaredLR. For the coxme()-fit ...
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1answer
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Setting up data for Survival Analysis in R [closed]

I am at the beginning of setting up a survival analysis in R. I took a look in this book here: https://www.powells.com/book/modeling-survival-data-9780387987842/ but struggle to properly set the data ...
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How to apply transfer learning using a survival model?

I have a parametric survival model assuming a certain distribution pattern for dataset A. I now wish to use the same model for dataset B. What criteria is needed to ensure that the model built on ...
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20 views

Different results for Cox regression

I am trying to get my head around Cox regression. I found quite a good paper on the subject by R. Tibshirani: A plain man's guide to the proportional hazards model. On page 67 he gives a toy example, ...
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Why is the exponential function used in Cox regression?

I am trying to get my head around Cox regression. I found quite a good paper on the subject by R. Tibshirani: A plain man's guide to the proportional hazards model. On page 66 he states: For ...
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Performing a Wald-test on Hazard-ratio without PH assumption

I have data on the duration of treatments. There is a disturbance at t=0 (treatment tariffs radically increase), which leads to an sudden increase in the number of treatments closed at that point. I ...
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How to graph a survival function when time is one of the IVs?

I am reviewing an article, so I can't be too specific, but the authors are doing a survival analysis of outcomes of stroke and one of the independent variables is the time that the person had a stroke ...
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How to compute CDF for Lognormal distribution survival formula

I would like to manually compute the lognormal distribution but I am not clear on how to compute the CDF value that is required in the formula for the Survival function. The formula is as below: $S(...
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Assessing loss of different parsimony levels (Cox Model)

I have a Cox Proportional Hazard model with 6 covariates to determine OS. I am now trying to simplify this model by taking some of this covariates down. This is intended for a wide audience so I'm ...
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Derivation of score vector

Can anyone explain the process of this derivation, step by step? This derivation is from Joint Models for Longitudinal and Time-to Event Data by Dimitris Rizopoulos. \begin{equation} \begin{aligned} ...
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Dealing with a statistically insignificant variable while AIC decreases when introduced in the survival analysis model selection?

I am new to survival analysis and currently very confused regarding a model selection process (forward stepwise) in cox proportional hazard model. What happens is basically the following step by ...
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1answer
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How to check data distribution fit for censored data in survival analysis?

I would like to check if the data I have follows a certain distribution and if I understand correctly, there are several statistical tests that can be used to determine this - Kolmogorov Smirnov Test, ...
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82 views

Bivariate exponential distribution $(S, T)$ with controllable correlation and $S\leq T$

I am trying to define a bivariate exponential distribution $(S, T)$ with marginals $S\sim\mathrm{Exp}(\lambda_S)$ and $T\sim\mathrm{Exp}(\lambda_T)$ for $\lambda_S > \lambda_T$. I would like the ...
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Survival Analysis and multiple observations

I am currently conducting a survival analysis for the first time and I am finding the conceptual aspects of the analysis a bit tricky. I have a hospitalization dataset that spans over a 20 year period ...
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1answer
52 views

Different Results From R's Survival Library and Python's Lifeline library [closed]

I have a dataset that I'm trying to perform basic K-M survival analysis on. I initially used the Python package lifelines to perform the analysis. To double check my results, I also then used the ...
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Hazard rate with exponential distribution

Hi I was trying to understand hazard rate and got stuck in the middle. Any suggestions are welcome. Below is the problem. Consider the following distribution for the duration of an unemployment spell ...
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Relation between ratio of two hazard functions and the survival function

I am given the following equation $$\frac{h_1(t)}{h_0(t)} = \frac{\theta_1\theta_2}{\theta_1+(\theta_2-\theta_1){S_0(t)}^\lambda}$$ and I am asked to find the role of $\lambda$. I have tried fitting ...
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Is it suitable to fit a Cox PH model for Life Data?

I have life data where experiments are conducted at different settings to observe machine degradation. A close example of how the data looks like is from this link: http://www.statvision.com/webinars/...
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An investigator planned repeated measures on n individuals with K time points but the sample size changes due to death-event after each time points?

Suppose an investigator planned repeated measures on n individuals with K time points but the sample size changes due to death-event after each time point. The investigator seeks to predict the cause ...
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At risk process in survival analysis

Why is there minus in $N_i(t-)$ in the risk process $Y_i(t)=1 - N_i(t-)$?
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ROC for time-varying covariates in ddhazard model?

i want to draw ROC for ddhazard model. I have tried risksetROC package. But i am unable to get predictors for my model. here is the code: OBTAIN A LINEAR PREDICTOR predict1<- predict(ddfit1,type =...
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How to correctly interpret Schoenfeld Residuals P-Value

I have been reading various responses on this topic but I do not yet understand how the p-value is interpreted to determine if the proportional hazards assumption holds or not. I have a global p-...