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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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Pseudoreplication problem

I am trying to analyse a data set with a pseudoreplication problem and would be grateful if someone could give me some guidelines on the best way to deal with it. We have a set of subjects exposed to ...
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5-year EFS > 5-year OS

I had a data of 24 cancer patients; their 5-year overall survival (i.e. event as death) was around 57%, however, when I calculated 5-year event-free survival for the same cohort, defining the event as ...
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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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Equivalence of Kaplan-Meier estimator and EM algorithm

For right-censored failure time data, in a non-parametric setting, is there an equivalence between using the EM algorithm (i.e. calculating the expected log-likelihood and maximizing) and the Kaplan-...
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km curve sample size at t=0 with censoring and events at t =0

How do I calculate the $n_t$ (subjects at risk) at each time t when i am dealing with a dataset that contains both events and censored data at time t=0. Assuming I have 248 subjects in a study to ...
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Number at risk for adjusted analysis

I need to plot cumulative incidence curves, which correspond to 1 - Kaplan-Meier-values. Doing so for a factor x with four groups gives me the following curves: But in fact, I have many variables ...
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How to do a survival curve adjusted to age in SPSS?

I have to do a survival curve comparing 3 diseases. Already did a Kaplan Meier since time of diagnosis, and the log rank was p-0.001; however I suspect that it has to do with age (one disease is ...
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Interpretation of beta Coefficients if Transformed in a Multivariate Cox Regression [duplicate]

I had to transform some of my primary variables of interest (log transform). Others were left untransformed as they were normally distributed in the sample (Pfat, etc.). To allow for comparisons of ...
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Survival analysis: why MEDIAN of third event outcome is NA always?

I am doing a survival analysis integrating gene expression based on normalized counts: a gene can be expressed at 'low', 'high', 'med' levels. Here is what I do: ...
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How should I decide which test to use to look for differences in Kaplan-Meier curves?

I'm conducting a survival analysis for my dissertation and have run into a bit of a road block about which test to use to look for differences in Kaplan-Meier curves between treatments. A previous ...
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Kaplan-Meier curve: Subjects with multiple follow up and event status

I would like to create a K-M curve for my data. My confusion is, I have some patients with multiple observed times and event status (see pic). Events under the same patients are independent. Would it ...
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Assigning weights for binary endpoint analysis, using survival analysis

This problem concerns the evaluation of predictors which could potentially be used to decide on which patients to perform colonoscopy. Study design: Analysis of administrative data - patients ...
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Why are Kaplan-Meier curves crossing when Cox PH assumption is not violated (Global Shoenfeld non-significant)?

I am not sure how to interpret the results given from the Cox PH model and the Kaplan-Meier curves. The analyses are conducted in R. In an observational study, 172 patients are categorized based on ...
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Deriving the Kaplan-Meier estimator with right-censoring

Let $\lambda_j$ be the hazard function for time $t_j$, where $j\in\{1, 2, \ldots, J\}$, and let $d_j, c_j$, and $n_j$ represent the number of "deaths", the number censored, and the number at risk at ...
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How to find probability of survival of a particular patient from kaplan meier plot?

Upon doing: kmsurvival <<- survfit(Surv(time, event) ~ Risk) I get a KM plot similar to : Now, for a particular patient in the data; say patient number 15,...
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Help with Right Censoring for survival analysis

Hi all I would like to do some survival analysis. The most difficult part for me is setting up the censoring data correctly and I would appreciated if someone can help confirm if I'm doing this ...
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91 views

Significant but very small beta coefficients in Cox proportional hazards calculation (survival analysis)

I'm analyzing TCGA data to investigate the effects of lncRNAs on survival. Among other things, I wanted to calculate a univariate CoxPH model for each gene to find genes whose expression levels have a ...
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Estimating survival curve when survival times are extremely different

I am analysing a dataset in a study on cardiac resucitation for sudden cardiac arrest. Almost 30% of patients die during the first two-three hours after cardiac arrest; these deaths are called in situ....
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Comparing two KM estimates outputs without raw data

Some raw data has gone missing, but I have the outputs of two KM curves - Both their survival estimates and patients at risk. Is there any way for me to use just the estimates to test the difference ...
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what is prediction error in survival analysis

I recently started doing predictive modeling in survival analysis. However, I'm confused about how to evaluate model performance. When comparing models, the reference is 'marginal kaplan-meier ...
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How to treat maximum remission time in survival analysis?

I am performing a Kaplan–Meier estimator to determine the probability of remission time before a relapse. I have seen many examples, typically using cancer as an example. These focus on the singular ...
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Should the Kaplan-Meier p-value be adjusted if new data are added?

The event of interest is subscription purchase and the time variable is days since the creation of the subscription trial within an AB Test. The stakeholders want to monitor the progress each day as ...
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43 views

survival analysis - Kaplan-Meier estimator comparison

I am working on an assignment. We are asked to compare the probability of not having an infection in 20 days with 95% CI vs. 20 days with 75% CI. To me this question seems very strange. I believe ...
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Generating frequency table and survival curve after multiple imputation

I'm using the MICE package to generate 10 imputed datasets. After that, I know I should perform analysis on each dataset (propensity score matching, Chi-square, and Cox-regression in my case) and ...
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Survival estimation with left-truncated data

I have some difficulties understanding the effect of the truncated data on my estimation of survival function. I am studying the survival for some "dependent" people (policyholder with Long Term Care ...
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Determining optimal cut-off from continuous variables using ROC AND applying it to Kaplan-Meier survival curves

I'm currently working on texture analysis of brain tumors and I've encountered a statistical hurdle. Data from texture analysis consist of 33 different continuous variables (A0-G10). ...
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Survival analysis: Missing Cox Regression Analysis

I came across a survival analysis that was conducted with Kaplan-Meier and log rank test alone. No Cox regression was performed. Am I correct to assume that there was an omission of the essential cox ...
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Kaplan-Meier with known censor distribution

I would like to know if you can do better than Kaplan-Meier when you know the censor distribution. I searched google but I could not find anything. This problem seems to be quite natural/useful when ...
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How to interpret a cumulative incidence function (CIF) as compared to the raw cumulative incidence

I'm trying to both describe and when and whether foreclosure occurs for home mortgages. This is an application where there are competing risks--if the borrower prepays (sells the house or refinances) ...
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261 views

Can the upper limit in a 95% confidence interval in a Kaplan-Meier survival estimate be above 100%?

I am in need of some help in understanding the 95% confidence interval for my survival estimates (Kaplan-Meier). For example, at 1-year my estimated survival was 0.929 with a standard error of 0.069. ...
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Surviving three years after surgery

I would like to calculate the probability of surviving three years after surgery. My dataset has four columns: date of surgery (surgery_date) date of death (...
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The Kaplan-Meier weighted generalized M-estimation

Consider linear regression model: \begin{equation*} y_i = x_i^T \beta + \sigma \epsilon, \end{equation*} where $y_i = \min(T_i,C_i)$ (failure time and censoring time). Can someone explain me the ...
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402 views

Interpreting Median Survival vs Median in survival data

I'm doing some survival analysis in R using the survival package for a patient cohort. When making a Kaplan-Meier curve using survfit, it reports a median survival time. However this value is very ...
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Calculation of person years in a cohort study for survival analyses

I am analysing data from a cohort study using primary care data (but I linked them up to secondary care data only for the outcome). Specifically, I am looking at the adoption of a specific care ...
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Visually Comparing the Kaplan-Meier Curve to the Cox PH Model Curve

I am conducting a survival analysis and have a few questions regarding it's interpretation with respect to the Cox Proportional Hazards Model: Why does the inclusion of different covariates change ...
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Kaplan-Meier estimates with missing data on non-survivors

As a hobby application, I want to estimate a Kaplan-Meier curve for "survival" of football referees, i.e., for how long they stick to this activity. I have data for when they started and, if ...
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Is it valid to calculate a kaplan meier curve for variables other than time?

Kaplan meier curves are usually calculated for survival probabilities over time. Is it valid to calculate kaplan meier curves for survival probabilities over other continuous variables e.g. over ...
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Removing NaN or replacing NaN by $0$

Suppose $\delta_i$ is a censoring indicator, $w_i$ is weight, and $\hat S(t_i)$ is Kaplan-Meier estimate. A part of an equation is $n^{-1}\sum_{i=1}^{n}\frac{\delta_i\times w_i}{\hat S(t_i)}$. For ...
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Parametric modelling of survival data: when there is no event in a long tail, is there information?

I have a survival analysis question. Let's take a look at the below curve: For the red curve, there are no more events after 48 months. For the black curve, there are no more events after 60-ish ...
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1answer
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will one treatment have an unfair advantage in my Kaplan-Meier comparison?

My data on cancer patients spreads over 18 years. The first nine years the patients are diagnosed with a CT scan. Then PETCT becomes approved. I want to do a survival analysis(Kaplan-Meier) and a ...
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How to word the interpretation of a Kaplan-Meier estimate

Which one (if any) of the below sentences correctly describe the interpretation of the median of a Kaplan-Meier product limit estimate of survival when the time-frame is the age of the study ...
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Kaplan-Meier curves seem to say otherwise than the Cox regression

In R, I am doing survival data analysis of cancer patients. I have been reading very helpful stuff about survival analysis in CrossValidated and other places and think I understood how to interpret ...
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Creating survival reference population

My first post on this site. I have a dataset with data about cancer patients. I would like to see how their survival is compared to a "normal population". I also have a table with information about ...
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1answer
45 views

Can I change number of people at risk during study in survival analysis?

I need to estimate the survival function using Kaplan-Meier method. I am considering the duration of 60 days. In the beginning (Day 1), lets say there are some 400 individuals. My question is: 'after ...
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Kaplan–Meier survival curves vs Nelson–Aalen cumulative hazard curves: interpretation

I have a right-censored data set. I plot a Kaplan–Meier survival curve using R: The y-values are easy to interpret, e.g. about 45% of the population will survive 500 days. Now I plot the Nelson–...
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Which Kaplan Meier Estimator to use?

I do have two data-sets and I am not shure which version of the KM estimator to use. Both datasets contain the following columns: ID | Issue Date | Last Recorded Date | Status Wheras the Status can ...
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134 views

Pointwise 95% CI for F(t) given Kaplan-meier estimate S(t)

I understand how to find 95% CI of Kaplan-Meier survival estimate using Greenwood's formula, and then using a log-log transformation so that the CI is bounded correctly. My question is, what are the ...
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How to display a Kaplan–Meier plot (survival graph) with hundreds of thousands of datapoints?

I made a library for displaying survival graphs. I am currently struggling with figuring out how to meaningfully display data with 300,000 data points. There doesn't seem to be enough pixels in the ...