Questions tagged [logrank-test]

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The link between log-rank test and KM estimates

I have taken the survival analysis class a few years ago, and we have learned both Kaplan-Meier estiamtes for survival curves, and the log-rank test for inferencing the difference of hazard rate ...
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Is log-rank parametric or non-parametric test, and why?

How is the log-rank test a "non-parametric test" according to wikipedia.org if one has to specify the parametric survival model for this test? We may run log-rank under the assumption of ...
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Does log-rank statistic converge in distribution to a beta distribution or Pearson I distribution?

The logrank test statistic compares estimates of the hazard functions of the two groups at each observed event time. It is constructed by computing the observed and expected number of events in one of ...
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1 answer
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How to conduct Cox-regression with time-dependent covariate and estimate K-M plots (including log-rank test)?

I want to conduct a Cox-regression with time-dependent covariate and other control variables and estimate K-M plot with log-rank test result. I will take the heart transplant as an example, some ...
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How do I interpret these results? [duplicate]

I have some data and have performed a long rank test using the survminer package in R: survdiff(Surv(survivaltime, status) ~ gene, data = data) I am effectively ...
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Why are there multiple formulas for logrank?

I've been studying the logrank test recently. The most common aid formulas that come up in searches are: But in Python and R, the logrank test seems to be done using the following formula: I know ...
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0 votes
1 answer
64 views

When having non-proportional hazards, should I use stratified Cox by time or Logrank tests within periods?

My data have non-proportional hazards with clear separation. Should I handle it via stratified Cox regression or using separate Log-rank test within subsets? I will use R only to illustrate. I want to ...
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23 views

Can I use Cox model to compare two survival function similarity like log-rank test? [duplicate]

My question is as the title emplies, can I use cox model to measure the difference (or similarity) of two survival functions, just as log-rank test does? And if so, how? Thanks in advance!
1 vote
2 answers
51 views

Median Survival Time for Clinical Trials

I have a Clinical Trial where I'll be comparing a drug vs placebo. Then I intend to run a Log-rank test on it. Now for the sample size calculations, I would be requiring the hazard ratio and the ...
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1 answer
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Sample size calculation for a three arm clinical trial study

I have a 3 arm clinical study with two drugs and placebo on the three arms respectively. I intend to perform a Log-rank test on it. I would like to know about the best software which is globally ...
1 vote
1 answer
150 views

Will stratified log-rank test work if there is no event in some small strata?

Since the analysis is for a rare event, it is possible that some small strata have no event. Hard to predict. Just wondering if there will be any problem. Cox PH model will have problem for sure, but ...
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1 answer
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Type II error for survival analysis

I am a beginner and I have been looking all over the internet and books to find an answer to the folowing question (but haven't been able to find the answer): I have observatoinal data and would like ...
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1 answer
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How to calculate the sample size for three groups (or >2 groups) by log-rank test in R?

We plan to conduct a study for comparing the survival rate between three different types of surgery for total knee arthroplasty. Thus, the sample size for the study should be estimated. Notably, how ...
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1 answer
20 views

Log-rank test: should I run it once for the whole follow-up or also test for shorter time periods?

Let's assume we have a 5-year follow-up for survival for two groups, and I report their crude mortality rates for years 1, 2, 3, 4 and 5. After that, would it be reasonable to test the mortality ...
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1 answer
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How to get adjusted logrank in the Cox model, if I have two covatiates?

Let's say I have a model (pseudolanguage): survival = My_Factor + sex + age. I do it to adjust the hazard ratio for sex and categorized age={<30yr; >=30yrs} (not my choice). I can get two p-...
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1 answer
245 views

R: Survfit function - getting p value when specifying start.time

I would like to make a Kaplan-Meier curve for data on an alternate timescale. I'm interested only on events happening after 6months followup, so I use the ...
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2 votes
1 answer
199 views

Why use a stratified log-rank test if we balance over strata anyway?

When comparing survival data over time, we can use the log-rank test. An extension of this is the stratified log-rank test, which adjusts for variables. Let's say we wanted to adjust for the effect of ...
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1 answer
2k views

How do I get 1-, 3-, and 5-year survival with survival analysis in SPSS?

I have a database with patients and did survival analysis in SPSS. SPSS gave me the mean and median survivals with 95% confidence intervals. However, I also want the 1-,3-, and 5-year survival times ...
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1 answer
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Test for difference in hazard in two consecutive time periods

Let's say I have data on times-to-failure for a group of mechanical components in two consecutive years, Year 1 and Year 2. I would like to test the hypothesis that the hazard rate/survival behaviour ...
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1 vote
1 answer
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Survival comparison among two different groups

I have two groups of patients, let’s say groups A and B, who have the same disease with a well-known genetic cause. My main goal is to see whether there is a difference in survivals by the type of ...
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1 vote
2 answers
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Is logrank test and its variations affected by the inequality of classes?

I am currently dealing with an home made exercise which compares the lifetime of patients who made use of a specific drug or not. For simplicity, I decided to remove censored data, but as replacement ...
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1 vote
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How to use log-rank test for panel data?

Is it possible, and if yes how, to compute log-rank test to compare effects in (unbalanced) panel data, i.e. longitudinal study ? What are the possible problems which might arise ?
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1 answer
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Survival Analysis when Independent Variable Proportions Shift Heavily Over Time

I am attempting to conduct survival analysis on hiring processes with Kaplan-Meier, where the event is termination from the organization: testing a few independent variables known at an employee’s ...
2 votes
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58 views

What is a dragon king?

I am studying a system of cities where the largest city appears to be in many aspects an outlier. The distribution of city size - in any country - are often claimed to follow Zipf's law. According to ...
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1 answer
101 views

Compare p-values of equal sample sizes: What does it mean if a p-value of kaplan-meier log rank test is larger than the other?

I'm analysing detection rates of carcasses for birds and mammals in either open fields or in forests, using kaplan-meier survival functions. The p-value is determined by log rank test. I found that ...
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3 votes
1 answer
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Which test should be used to compare crude mortality between 15 groups?

I have fifteen groups (factor levels) and I need to compare their crude mortality. Is Logrank test limited to two groups only? Which test would be correct to use in this case?
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3 votes
1 answer
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The logrank test statistic is equivalent to the score of a Cox regression. Is there an advantage of using a logrank test over a Cox regression?

I have understood the logrank test as a "safe" or "conservative" way to check for a difference between two survival curves. It is "safe" in the sense that it is a ...
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1 vote
0 answers
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Question on svylogrank() in survival package

I am running a survival model with sampling weights and was hoping to get the weighted logrank test results. When I use the svylogrank() function from the survey ...
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1 vote
1 answer
776 views

Difference in log-rank, tarone-ware, gehan-breslow, Peto-Peto etc

Everything is already in the title. I study survival analisys Could you tell me what is the difference among log-rank, tarone-ware, gehan-breslow, Peto-Peto etc.....
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1 vote
1 answer
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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 ...
3 votes
1 answer
3k views

Why is likelihood ratio test preferred Cox model for small sample sizes?

It looks like a common consensus that likelihood ratio (LR) test is preferred over log rank and Wald in Cox model when sample size is small. I did some research and couldn't find any clear answer My ...
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2 votes
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562 views

Why are Logrank, Wald and likelihood ratio test asymptotically equivalent?

I am trying survival analysis and it seems like a common consensus that Logrank, Wald and likelihood ratio are asymptotically equivalent I don't understand why they are asymptotically equivalent. As ...
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4 votes
1 answer
613 views

How to calculate log-rank test statistic

Depending on which statistics text you read you will get 2 different formulations of the log-rank test statistic. In some texts you will see it specified as: $$ \frac{(O-E)^2}{E} $$ Example 1 Whilst ...
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2 answers
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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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63 views

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 ...
0 votes
1 answer
123 views

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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1 answer
2k views

R calculate log-rank p-value of survival curve at specific time [closed]

I am using survfit object from package survminer to draw a survival curve in ggplot. Now I am trying to understand how I can use ...
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2 votes
1 answer
8k views

Logrank p-value for >2 groups

I'm reviewing a paper that includes some survival plots for patients stratified to 3 groups (low, intermediate and high value of certain parameter), with p-value given for each plot. My understanding ...
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1 vote
0 answers
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Cox Regression Model for toxicity

I'm trying to evaluate the toxicity of a certain treatment over time. I have 2 independent groups and I apply a treatment to one, and nothing to the second one. I thought about using logistic ...
1 vote
0 answers
403 views

Survival Analysis: Significance in LogRank but not in Cox Regression

Currently, I am trying to extract the HR and 95% CI from a kaplan meier curve (used DigitizeIt plus the spreadsheet provided by Tierney et al) [Tierney JF, Stewart LA, Ghersi D, Burdett S, Sydes MR....
3 votes
1 answer
251 views

How to deal with different likelihood of censoring across groups in survival analysis?

I am analysing survival data for nematode worms fed on four different bacterial diets (four groups). Each group has at least 70 events (deaths), but there is often a very uneven proportion of ...
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1 vote
1 answer
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sample size calculation for one-sample log rank test with interims (ie group sequential)

I wonder if there is any advice for performing a sample size calculation for survival data using the one-sample log rank test with interims (ie group sequential) - ie with O'Brien-Fleming or some ...
1 vote
0 answers
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Is Univariate comparison of 10 subjects using log rank test in Kaplan Meier survival is statistically sound?

I have 10 subjects and want to analyse the predictors of overall survival and progression free survival using log rank test . Will conducting log rank test on such a small sample size will be ...
1 vote
0 answers
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A strange finding with the logrank test statistics

When I try to confirm the type I error rate of the logrank test by simulation, I found something strange... Firstly, I generated 100 observations from exponential distribution with lamda1=1 as group 1 ...
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1 vote
1 answer
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Can coxph be used for categorical data?

I'm doing some survival analysis and I got the idea to change a binary variable into three-category variable by sub-dividing one category of the binary variable into two new categories. Here's a ...
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2 votes
1 answer
391 views

Version of Mann-Whitney U test, for right-censored data

Is there an equivalent of the Mann-Whitney U test, but for right-censored data? I have right-censored numerical data from two different groups. The mean for one group is higher than the other. I'd ...
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2 answers
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how can I focus the log rank test in a selected period of time of follow up?

I am using R survdiff (survival package). I would like to focus the analysis on the first 2 years of my survival curve (that is actually much longer, but with few cases in the long term and with ...
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1 vote
1 answer
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Uneven (right) censoring where the time of truncation is constant

I've collected data comparing the relative success of two different groups of participants on finding the answer to a difficult question. The problem is that not all the participants in the control ...
1 vote
0 answers
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Is there a reason chi square tests are used over normal tests in survival?

I've been reading and programming a bit about survival, and it seems that a lot of statistics are normally distributed (and thus, their square is chi square distributed). For example, the log rank ...
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Reproducing the cox model score test in R

I am using R and would like to recreate by hand the values of the tests. For example, ...
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