Questions tagged [logrank]

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How to perform a stratified logrank test in R [closed]

Suppose I have two matched sets with n = 50 each. I've arranged them by an ID variable such that each ID variable has 2 subjects. I'd like to compare overall survival with a kaplan meier accounting ...
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7 views

Survival Analysis - log-rank test

I'm comparing the survival curves of two treatment groups. For the most part of the time period, the two curves are similar with largely overlapping confidence intervals. This is true until a later ...
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10 views

Derivation for the sample size formula of log-rank test in Cook and DeMets book page 129

Can anyone give me some hint on the derivation of E(xj|nj1,nj2), EU and VarU as shown on page 129 in the book "Introduction to Statistical Methods for Clinical Trials"? This is supposed to be a ...
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1answer
25 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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8 views

Noninferiority for logrank test

I have two samples with censored survival data, adjusted via propensity score matching. I want to compare them with logrank test or something like that (but not with a Cox regression). Can I use ...
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1answer
45 views

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 ...
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1answer
284 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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0answers
121 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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1answer
141 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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2answers
66 views

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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0answers
55 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 ...
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1answer
66 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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1answer
821 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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1answer
2k 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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0answers
41 views

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 ...
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0answers
200 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....
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1answer
107 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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1answer
138 views

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 ...
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69 views

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 ...
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0answers
65 views

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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1answer
630 views

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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1answer
238 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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2answers
627 views

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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1answer
57 views

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 ...
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0answers
86 views

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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664 views

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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1answer
2k views

Survival analysis: log rank or ANOVA to compare groups?

If I want to know whether there is a significant difference in age of onset between the 2 groups, should I use ANOVA? My data meet the requirements of an ANOVA test. Or should I use the log rank test, ...
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1answer
789 views

One-Sample Log-rank test statistic

Ok, I am totally confused, this is probably a pure math rather than a statistic question but please enlighten me. I found the logrank statistic formula being reported in the literature in 2 ways, but ...
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3answers
428 views

How can you have p < 0.0001 with a sample size of 89 and a control group of 52?

From Efficacy of monoterpene perillyl alcohol upon survival rate of patients with recurrent glioblastoma (linked from Does Frankincense cure cancer?): Patients and methods It was included 89 ...
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0answers
457 views

Survival probability for a case-control study

I have a case-control study in which 21 patients with a certain clinical outcome and 20 patients without that clinical outcome were (retrospectively) selected from a larger group of patients who were ...
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0answers
56 views

Very puzzling - naming the endpoint of survival analysis

A question that should be straightforward for statisticians but is puzzling me to the point I am nervous. I am doing a PhD in Epidemiology and am going to use Cox regression. The predictor is a ...
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1answer
538 views

Relative Risk with Log-rank test

I always associated/used log-rank test to evaluate Hazard Ratios. However, a well-known professor is using/presenting results of log-rank test for Relative Risk and Risk Ratio. Can anyone explain ...
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897 views

Matlab survival curve log rank test

I am trying to do survival analysis in matlab and want to calculate log rank test scores among several curves. I found a possible code to do log rank here. But based on its description, it can only do ...
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2answers
10k views

How to calculate the HR and 95%CI using the log-rank test in R?

The R survival package is very useful to do survival analysis. And I know the survdiff function can be used to compare the difference of survival time in two or more groups. And the p-value number can ...
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2answers
2k views

Log-rank / Cox analysis with very unequal sized groups: alternative calculations of p-value?

I would like to set up a series of tests on the difference in survival between two very unequal sized groups. Generally either log-rank (using the R survdiff function) or a cox regression (R coxph) ...
4
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2answers
22k views

log-rank test in R

I need to use the survdiff function to statistically compare (using log-rank test) the following survival functions: (1) Male (Sex=1) and Female (Sex=2) (2) ...
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2answers
3k views

Logrank test for trend (proportional hazards)

How one can create a logrank test for trend and does it differ from normal logrank test? Any suggestions or literature? Maybe some R examples and functions?
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1answer
549 views

Validity of Log-rank p-value when there are zero events in one group?

I am looking to do a Kaplan Meier analysis to look at survival in two groups. I have 21 people in group A and 17 people in group B. 5 people in group B died at various times, 0 people in group A died, ...
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1answer
3k views

Sample size / power calculation for logrank survival test

I have really little idea of survival analysis. I am aware that logrank is a special case of Cox' proportional hazards model, and that tons of R packages and scripts address the problem of power / ...
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0answers
95 views

Error in books formula concerning the log-rank test?

I am currently reading the following book: Clinical Trials: A Practical Guide to Design, Analysis, and Reporting by Duolao Wang, Ameet Bakhai (2006) On page 243-244 there is an example about the log-...
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1answer
2k views

In which situation does the log-rank test have low power?

This question is complementary to question 1 asked by @Jesse here. It is about the case when we don't find a significant result when performing the log-rank test and when the proportional hazard ...
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2answers
718 views

Combining several survival experiments

In four independent experiments, two strains (A and B) were compared in their respective survival curves. Two experiments show a clear-cut result (A survives at 100%, almost half B dies). Two further ...
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1answer
11k views

Difference between survdiff log-rank and coxph log-rank

I'm using the survival package in R to analyze clinical data. I am analyzing two different groups of patients, when I calculate survdiff in order to compare the curves, I got p= 0.135, but when I ...
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0answers
347 views

How do I compare 2 models?

I would like to show that a new biomarker (let's say percent tumor volume reduction at 3 weeks of treatment estimated with automatic methods) performs better than an old one (same measure, but based ...
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4answers
3k views

How best to analyze length of stay data in a hospital-based RCT?

I am interested in knowing whether or not there is a consensus about the optimal way to analyze hospital length of stay (LOS) data from a RCT. This is typically a very right-skewed distribution, ...
6
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2answers
2k views

Which algorithm to compute p-value of logrank test with three or more groups is best?

There seem to be two different algorithms for comparing three or more survival curves using the logrank test. Algorithm A. Found in books by Altman and Machin. Computed by GraphPad Prism. This ...
6
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2answers
4k views

How should I deal with the consequences of proportional hazards violations in log-rank (and related) tests?

I have (censored) time-to event data for subjects in four groups. I would like to do something like a logrank test, but the survival curves do not satisfy the proportional hazards assumption. I ...
4
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1answer
615 views

Is there a repeated measures aware version of the logrank test?

I am looking for a repeated measures version of the Logrank test. If I am correct, I am looking for an equivalent of the Friedman test for survival data. Any suggestions on where to look? (and R ...