# 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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### 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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### 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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### 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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### 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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### 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 $Y_i(t)=1 - N_i(t-)$?