# survival analysis

1. ### Significance between ratios?

I'm performing a survival analysis where I compare between 2 conditions in one cell type (cell type 1) vs two conditions in the other (cell type 2). The "Recovery factor" = Survival Condition1/Survival Condition2 Survival Condition1 and Survival Condition2 are each calculated from the mean of...
2. ### Survival Analysis with two types of event

Hi, guys! I'm looking for an example of kaplan meier with two different types of event, e.g. tumor progression or death as outcomes. Somebody knows a paper where two outcomes were reported in same KM curve? Thanks A
3. ### Help with RPSFT model implementation in SAS

Hi! I am doing an analysis on overall survival endpoint. The patients in the placebo group will be switched to treatment group in the open-label phase on voluntary base. I plan to use Rank-preserving structural failure time method (RPSFT) model. Is anyone familiar with this method and know how...
4. ### discrete time survival analysis

I would greatly appreciate if you could let me know how to do discrete time survival analysis with time varying covariates. Some part of my data set is as follows (d1-d12: are dummy variables for each time period): ID TIME EVENT x1 x2 x3 x4 x5 1 1 0 1.28 0.02 0.87 1.22 0.06...
5. ### Rewriting integration by summation

Suppose that n individuals have lifetimes represented by random variables T_1, T_2, \ldots, T_n. Instead of the observed values for each lifetime, we have a time t_i' which we know is either the lifetime or censoring time. Let us define a variable \delta_i=I(T_i=t_i') that equals 1 if...
6. ### propensity matching and ITT for cohort study

I am reviewing a cohort study that used a retrospective database to determine if treatment with hypothermia post cardiac arrest improves survival to discharge. They used what seems like fairly robust propensity matching analysis. However they then adjusted afterwards again with sensitivity...
7. ### Area under Kaplan Meier curve

There is one thing bothering me for some time: What does area under Kaplan-Meier survival curve actally represent? Is there a plausible way to compare two areas under curve when for instance two curves cross late in follow-up and invalidate the use of log-rank test due to violation of...
8. ### logistic regression or survival analysis?

Hello, I have two main questions that I hope you help me answer. Let me give you the scenario first. Let’s say that some students in a school are assigned to 3 different programs after being involved in a fight. The aim of the program is to prevent students from fighting with each other. My...
9. ### Recurrent Event Survival Analysis

Hi there, I'm working on a research on individuals who enter financial distress using the Cox proportional hazards model. In this case the individuals can get in financial distress multiple times within a time-window such that independency assumption is probably not satisfied. I stumbled upon...
10. ### External Validation of Cox Model

I have two data set (training and validation) for building and validating a Cox model. With the training data set I fitted a cox model using stepwise selection method. The significant variables in the model were the only variables included in the validation model. Is this the right...
11. ### Kaplan meier: hazard and 95CI

I have conducted a time to event analysis with the kaplan-meier method and my instructor requested for HR and 95%CI of specific time points such as 1 year or 3 years. However the life table in Kaplan-Meier analysis lists me the cumulative survival for time points at which last follow-up occured...
12. ### Cox regression survival analysis

Hi, I am currently undertaking my dissertation and wondered if you could help me with some data analysis from one of my studies. The study indicates that they use Cox regression for survival analysis Results indicate that for group differences in depressive episodes the hazard ratio =0.38 95%...
13. ### Creating Graphs from Survival Analysis Outcome

If I run a survival analysis, how can I graph the output/outcome? I.e. if I run age group and incidence of a certain disease ('cancer'), and get a rate ratio for each age group, how can I put the RR on a graph with agregroup on the vertical and disease rate on the horizontal? I am...
14. ### Kaplan Meier Curves With Repeat Events? Is it Possible?

This may be a stupid question, but: can you construct Kaplan-Meier curves for repeat event data? Or should I limit each individual to occurrence of the first event? Thanks so much everyone! -Laura
15. ### Looking to test the equality of 2 survival curves with a Kolmogorov–Smirnov test

I am using R version 3.2.2 and RStudio version Version 0.99.486. Which R code can I use to test the equality of 2 survival curves using the maximum difference between the curves? This is like a Kolmogorov–Smirnov test statistic but not for goodness of fit. Previously I have used proportion...
16. ### survival analysis - concerns about duration times

Hello, I'm very much a beginner at survival analysis - i know the basics, but I still get a bit lost when it comes to details. I am researching the survival of authoritarian regimes (so not countries) under different conditions (let's call them Y). My data includes information on all...
17. ### Conflicting Results Evaluating Proportional Hazards Assumption

Hello, Currently working on a survival analysis of some lung cancer patients. I am building a Cox PH model and was working on validating the PH assumption for my covariates. To do this am using two techniques. Looking at the -log(-log(s)) plot of the survival function and also looking at the...
18. ### Predictive model for Turnover - Correlation or Survival Analysis

Question 1 - I a working on developing a model to predict employee turnover. The variables that I have are age, tenure, job satisfaction, role clarity etc. Through research papers I have found the correlation coefficient for these variables but I am not sure on how to develop a model around it...
19. ### Calculating life expectancy for cancer patients

Hi all I have been asked to use life table analysis to calculate life expectancy for cancer patients from birth. I am comparing 3 different groups - 1. diagnosed 1980-1990, 2. diagnosed 1990-2000 3. diagnosed 2000-2010. I have follow up data until 2013 for each group. I feel that I...
20. ### Using survival analysis to predict scope of truncated data

I'm not sure I'm thinking about this correctly, and would be grateful for any insight as I think the problem is analogous to one that comes up in biostatistics. I have data on payment to attorneys for representing clients (at public expense). I only learn about the existence of the...