Questions tagged [kaplan-meier]

The Kaplan-Meier estimator is a common non-parametric method for survival analysis and for plotting survival graphs. The survival function $S(t)$ calculates the probability of survival past time $t$. It is most useful in comparing the survival of different groups while properly handling censored data.

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11 views

Time Zero in Survival Models

I'm debating about where to start the time zero of my survival analysis. I'm currently trying to assess whether there are survival differences between a treatment vs a placebo for an acute disease in ...
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Understanding hazard, hazard rates, and the Kaplan Meier Estimate using a simple example

I'm struggling with understanding hazard in the context of survival analysis. Unfortunately I can't find any example calcuations online with simple values, and I struggle with the respective equations,...
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how to analyze data where one levels of treatment is left censored and other levels of the treatment are right censored?

I have data from an experiment where we looked at the time-to-death of pseudoscorpions under three treatment conditions: control, heat, and submersion underwater. Both the control and heat groups were ...
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Baselines comparison for Cox regression & Kaplan-Meier

If I am not mistaken baselines for Cox regression & Kaplan-Meier are equal ...
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Interpretation threshold utility analysis for quality adjusted survival time

I am having trouble with the Interpretation of this figure. In this study Survival time of patients was split up in 3 Intervalls: TOX, TWIST and REL. TOX is time with Treatment side effects. REL is ...
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Type II error relevant limitation when Kaplan-Meier curves are identical?

Let's suppose that we have a made-up data including two diseases, and one of them is very rare (impossible to get a large sample size). Kaplan-Meier curves of the two diseases are almost identical, ...
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Fitting a Survival Function with OLS - What Points To Use?

I'm trying to fit a survival function that is generated from discrete data. Is it correct to use Ordinary Least Squares, and if so what points do I use to do the fit? A, B or C? Or other? Or am I ...
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Extract sample variance from svykm (survey package by Lumley) for complex survey analysis

In order to compare two survival curves at a fixed point in time and perform basically a two sample test, I need to extract the sample variance of the estimate at a given point in time. For an object ...
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“survival” doesnt show in my survfit function in R [closed]

I am trying to calculate the 5 year overall survival in my dataset. I have used the survival package in r. Here is my code: <...
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Selecting study design ( and tests) to precise the optimal interval of checkups of engine to prevent engine major failures

I'd like to get your advice on how to select methodology and plan database variables (skeleton ) to conduct a retrospective research. there are around 60 engines, they can have major failure (main ...
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How to present KM estimate for mean and median survival times for those with small no. of events?

I wanted to obtain the mean and median survival times using survfit and Surv but due to the small event size, I can't obtain ...
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help undestanding coxph output

First thank you for taking time to help me! I appreciate it. I wouldn't be here unless I didn't feel like I was already spinning my wheels. I'm trying to learn more about survival analysis and coxph....
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83 views

Survival Calculations

I am trying to calculate survival rate for all grades (Kindergarten to 1st Grade) of school. See the example below for Grade 1 students. Y0 refers to number of students enrolled in grade 1 in that ...
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What does median survival mean in the context of a Kaplan-Meier estimator?

I have run a Kaplan Meier estimator with the survival package and it gives a median. ...
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Trial design to minimize expected p-value of Kaplan–Meier estimator of mortality for fixed N?

In randomized controlled trials, mortality is often compared between treatment and placebo using the Kaplan-Meier estimator (for instance, the remdesivir trial ACTT-1). The trial design could have a 1:...
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How to model covariates in Cox Regression with few events

for an oncology-related study I am looking to find out, whether a certain dichotomous variable (Status X) predicts outcome in a multivariable cox regression model (expressed as hazard ratios). Using ...
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Time to event analysis - median (IQR) is <75% experience event

I am plotting the Kaplan-Meier survivor function for time to event & will estimate the median survival. I want to present this with the IQR. If the resultant KM looks something like the below &...
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93 views

Extended Kaplan-Meier for time-dependent covariates

I have read Snapinn et al. paper on "Illustrating the Impact of a Time-Varying Covariate With an Extended Kaplan-Meier Estimator" (https://doi.org/10.1198/000313005X70371). They describe an ...
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Should the kaplan meier curve of an training data match the kaplan meier curve from the output of a Weibull AFT model?

I am running a Weibull AFT model for survival prediction. I am considering the predicted median value as expected Lifetime/output. To check if its following the same decay of out original user, I am ...
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Kaplan-Meier IPCW

My dataset is composed of n individuals (patients) with a two-year follow-up at maximum. Every patient is sane at the beginning of the study, and each month we note if the patients got a certain ...
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Can I conduct Kolmogorov-Smirnov test on censored data?

Normally, Kolmogorov-Smirnov is conducted on full, uncensored data with test statistics. $$ sup_x |F(x)-F^*(x)| $$ Or equivalently, $$ sup_x|S(x)-S^*(x)| $$ ,where $F(x)$,$S(x)$ is proposed ...
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Interpretation of Cumulative Incidence Function after Fine & Gray competing risks regression

I am looking at a 2 arm treatment trial, where recovery is the event of interest, with death as a competing event. After running a Fine & Gray competing risks regression I calculate the CIF using ...
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Can you build a Kaplan-Meier estimator from a training set and use it for predictions on a test set?

Consider a dataset with about n = 500 time-to-failure measurements, of hardware components, recorded with p = 20 features. Is it possible or sensible to take the dataset, split it into a training set ...
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Kaplan-Meier Estimator/Plot on cumulative incidence going from 0

I recently came across Kaplan-Meier curves while reading articles on COVID-19 and I did some basic readings on it given my limited knowledge on advanced statistical methods. The Wikipedia page ...
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167 views

Survivor function for log logistic from survreg output

I am trying to plot/generate a survival curve in Excel using the output from survreg in R. The below is a snapshot from R, I am not sure what to do with the values, how do I convert to the two ...
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Survival analysis with groups of related subjects

We conducted an experiment with approx. 5000 websites that had a specific issue. We looked up the operators of these websites and notified them of the issue, split into several experimental groups. We ...
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Distribution of censored data with Kaplan-Meier

I have a set of right censored data from a variable $T_{out}$ that expresses the survival time of a patient. In order to understand the distribution of this random variable, I used the Kaplan-Meier ...
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Measuring the risk of an event among hospital patients in survival analysis: should you censor patients who do not have the event?

I am trying to plot the risk of self-discharge from hospital over time ('self-discharge' means leaving hospital against the wishes of your doctor). In my data, hospital patients have a duration of ...
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Survival Analysis with right-censoring

I have the following data, which represent the realizations of the variable T = min(Y, C). Some of the data is right-censored (+) ( 5.3, 12.1+, 11.7, 10+, 2.2, 9.8, 9.2, 3.5, 5.7+, 9.2, 3+ ) To ...
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Calibration plot for survival analysis (Cox regression) using R [closed]

I have been working on developing a Cox regression model and was trying to create a calibration plot after binning the predicted risks into deciles of risk. I have the following code: ...
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Comparing Survival At a Fixed Time Point

For context, I have a data set of 600 patients from 2004 to 2018. In 2016 there was an intervention and so I currently have my data divided up as pre-intervention (n = 400) and post-intervention (n = ...
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How to account for dependencies in survival analysis of PS-matched cohorts with replacement?

I work on data from a cohort study (n = 3100). We want to compare outcomes of individuals with a special condition (n = 300) and their matched controls. I estimated propensity scores and used genetic ...
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Why should the right-censored observation be excluded from demonimator in KM estimation

It is well acknowledged that we cannot extrapolate the lifespan T of the censored observation. In the Kaplan-Meier estimation, the estimated $s(t)$ for $t∈[t_j,t_{j+1}]$ is estimated using: $$\hat{S}(...
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Choosing strata in stratified log-rank test

Let's say I would like to see which factors affect the survival of patients suffering from cancer. And let's assume I have two variables: chemo ($0$ - if a patient is not treated with chemotherapy or ...
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Predicting Survivor Times in a time series

I’m looking to analyse a Survival data event relating to lottery draw data. The event being is the time taken for two of the six winning numbers to be drawn again. A table of the data is shown as ...
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How to know event in kaplan Meier?

Below is the Kaplan-Meier curve for analysis of minutes from hospital admission to patient being setup in an ICU bed. For this analysis, what’s the event? What’s the time origin? Describe what the ...
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Survival Analysis results are counter intuitive, where am I going wrong?

I am using Survival Analysis to analyse a data set, but i'm having a bit of trouble. The data consists of everyone who has/has not been terminated from employment within a 4 year period. The aim of ...
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Non-time variables in the place of time in a survival analysis

I am new to survival analysis, but think it might be useful for what I'm trying to model. Essentially, I am trying to look at the probability of when certain types of words first appear in the book, ...
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29 views

Logistic Regression or Survival Analysis

I am trying to analyze typical time to crack initiation on roads. I know a little about survival analysis but I am not sure whether it is applicable in my case, as explained below: My data set was ...
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72 views

Integrate Kaplan-Meier estimator quickly in R

I am searching for R code for computing the following integral $\int\limits_t^{a}(x-t){\widehat S\left( x \right)dx}$, where $t$ and $b$ are fixed constants and $\widehat S\left( x \right)$ is the ...
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Study time period in retrospective survival analysis

I would like to calculate a Kaplan-Meier curve for a retrospective study. I will use the survival and survminer package in ...
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87 views

Adjusted Kaplan Meier in STATA : stcurve or sts graph adjustfor

I've been asked by a reviewer to plot an adjusted Kaplan Meier graph. I understood that with sts graph and adjustfor, the adjustment was to zero values of all the variables. So I tried to use stcurve,...
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40 views

Why univariate Cox does not have its own survival curve and has to use KM curve as approximation?

I am aware that KM-estimator and Cox model use different method. However, I am under the impression that we show KM curve as approximation of univariate Cox model. My question is why univariate Cox ...
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59 views

Relationship between KM-estimator and Cox model

What is the relationship between KM-estimator and Cox model? What I am aware is that Cox model allow us to adjust covariates. If I build a Cox model and draw a KM curve (using survdiff function). ...
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40 views

Truncation versus censoring with Kaplan-Meier

I am trying to run Kaplan-Meier on a rather odd dataset and am having difficulty determining whether I should be truncating or censoring my data. I have looked at the other feeds, including this very ...
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Interpretation of Kaplan-Meier curves with several groups in R [closed]

Got an assignment that we should interpret different Kaplan-Meier curves and the ouput from R looks like this: . The P-value tells us if the Groups are significantly different from eachother(correct?)...
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118 views

Advantages of using Cox model versus logistic GEE?

What are the advantages of using Cox proportional hazards model versus logistic GEE? Can one generate Kaplan-Meier remainder estimator curves using logistic GEE?
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Personal-Level Data vs. Time-Series Data for Kaplan Meier Survival Analysis

I currently have a person-level data set. By which, I mean each data entry is the most recent information about that individual. I have 350 thousand individuals which means I have 350 thousand data ...
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Kaplan-Meier and Cox in R give different results

Please, can you explain, why these two formulas give different answers? Is this because Cox is a semi-parametric method and KM is non-parametric one? I marked the differences with asterisks. Kaplan-...
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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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