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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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Survfit function with regression

I'm having trouble understanding what estimator the survfit function produces. For example, if I call ...
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Why median is NA for some of the group outcomes in survival analysis?

I'm trying to do survival analysis using the Followup information, patient_vital_status and the expression of gene. I'm using like below: ...
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Relation between hazard function and Kaplan-Meier survival curves

Could someone please explain intuitively and mathematically the relation between hazard function and Kaplan-Meier survival curves? If there is a relation, please give and example of deriving one from ...
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How to properly do a Survival analysis - Question about start times

I have a monthly report that lists transactional errors made by facilities all over the country. Each row is a single error and the columns represent descriptive information about each error (ID, ...
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Schoenfled Residua test shows proportionality hazard assumptions holds but Kaplan-Meier plots intersect

"If Kaplan-Meier plots cross each other then proportional hazard assumption does not hold". The issue I am facing is that I got the Kaplam-Meier plot(bleow). We can clearly see that it is overlapping. ...
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Survival analysis of two dependent variables (hatching time and total life duration)

I strive to find the best approach to analyse survival data from an experiment where random samples of fish eggs (sample size 30) were put into 3 different solutions of 8 heavy metals (total 24 ...
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Log-rank test for survival data in counting process form in R?

Background: at half-year follow up times for 4y, patients may switch to a different medication group. To account for this, I've converted survival data into counting process form. I want to compare ...
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Multi State Models to analyze/plot disease progression and probability of being misdiagnosed

Let's say that I have the following dataset containing information for 100 patients that have been followed up for a certain number of years to check if they develop a certain disease. We know up-...
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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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How to statistically split a set of numbers into two groups for Kaplan-Meier plot?

I want to perform a survival analysis for the cohort of breast cancer patients. For each patient, I know whether he was right-censored or not and what was his survival time (or the end-of-study time ...
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Survival Analysis: Number of Censored Events in Life Table [closed]

I want to construct a life table for some event of interest. See below for an example: I'm trying to do this with survival R package: https://cran.r-project.org/...
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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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Fitting Probability Distribution to Failure Data with discrete, right censored stress

I'm a bit unfamiliar with survival analysis and I'm struggling to find examples of the particular problem I wish to tackle (which I don't think is particularly unique actually). Imagine I'm doing a ...
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How can we analyze a dataset with a 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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1answer
123 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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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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68 views

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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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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176 views

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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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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1answer
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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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1answer
520 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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130 views

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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312 views

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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168 views

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 ...