[Cox proportional hazards regression][1] is a very popular, semi-parametric method for survival analysis.

learn more… | top users | synonyms (1)

0
votes
0answers
9 views

Imposing follow-up time cutoffs on censored data for cox regression

When fitting cox regression models, is it valid to impose a cutoff for censored samples to have been followed for at least a given stretch of time for inclusion in the analysis?
1
vote
1answer
22 views

What model fit / predictive accuracy measure can be used to cross validate a Cox PH model with censored data?

How would you go about validating a Cox PH model with censored data? I am trying to run a Cox PH model on a dataset with observations that failed, and observations that are censored. Normally, I use ...
0
votes
0answers
2 views

Best packages for Cox models with time varying covariates

I am working on a project using Cox models with time varying covariates. My questions are: What are some good examples of conducting this analysis? What is the best R package to conduct this ...
0
votes
0answers
12 views

How can I make an ANCOVA in R (Prior to a Cox ph model)?

I want to make an ANCOVA analysis of the survival rate of flies after being on a bad diet for the first 21 days of their lives compared to those always on a normal diet. I have studied the responses ...
0
votes
0answers
5 views

Modelling credit risk by Ornstein Uhlenbeck process incorporating macro economic variable

I have a data set on default, application score and some macroeconomic variable, I want to model the next default as poison process whose parameter is itself random, it comes from an ornstein ...
1
vote
1answer
20 views

How to calculate adjusted HR?

What is the difference between crude HR and adjusted HR in Cox regression? How do we calculate adjusted HR?
1
vote
0answers
21 views

Can Cox models be used with time-varying covariates?

I work at a hard drive manufacturer. In my project, we have huge sets of testing data of hard drives. Most of them are time-varying covariates. My colleges are using cox regression. I doubt it. ...
0
votes
0answers
30 views

Cox regression with two dependent expanatory variables

I am doing a Cox regression to model how survival times of sick patients, after taking a certain number of pills. There are in total 10 different pills patients can ...
0
votes
0answers
7 views

scaled Schoenfeld residuals slope of regression line

If a regression line of scaled Schoenfeld residuals versus time (or log time) has a non-zero slope, proportionality is violated. However, what can we tell from the slope of the regression line? If it ...
3
votes
1answer
23 views

Schoenfeld residual independent of time?

I've seen it claimed (e.g. in these notes ) that "Schoenfeld residuals are, in principle, independent of time." Can this be right? Consider the following situation: You are using a Cox model to ...
0
votes
0answers
26 views

Age-matching for 2 samples in Cox Regression

I have 2 samples with a very significant mean age difference: Sample0: less-invasive,lower-risk surgery. mean age = 70. n=159 , deaths = 24 Sample1: higher-risk surgery. mean age = 60. n=86, deaths ...
0
votes
0answers
15 views

using caret and glmnet for variable selection

Im using the caret and glmnet package for variable selection. I only want to find the best model and the coefficients and use ...
1
vote
0answers
19 views

Interpretation of coefficients of glmnet - LASSO/Cox model?

I have done a LASSO / Cox model run for a large dataset of 10K observations which has 1200 Variables. ...
1
vote
0answers
33 views

Comparing different methods of discrete-time survival analysis

I'm investigating a discrete time survival problem (the units are months and exit times range from month 1 to 36). From looking around so far, it seems like there are a few different types of model ...
2
votes
0answers
35 views

Which model to use for survival analysis when there are different times of entry into the sample?

I have a data set containing the trades executed by many traders as follows: ...
0
votes
0answers
29 views

Cox model with different follow-up times in groups

We have a dataset where the non-exposed group has follow up to 5 years but the exposed group has follow up only to 1 year (>1 year not possible in the dataset). Analysis is with Cox regression. ...
3
votes
0answers
44 views

Differences between logistic regression parameter estimates and Cox-proportional hazard parameters

We have been working on a survival analysis. We are examining tree seedling survival over a decade with annual to biannual census intervals. We have been using the package coxme in R for a mixed ...
0
votes
0answers
11 views

Regressing scale parameter of Weibull distribution against covariates

To handle clustered survival data w.r.t. a set of covariates $\mathbf{z}$, it is conventional to introduce Cox's proportional hazard rate or Accelerated failure time models. If a parametric baseline ...
0
votes
0answers
10 views

How to calculate Focused Information Criterion in R for Cox proportional hazards models? [migrated]

I am utilising R to perform a multivariate Cox survival regression for a research project. As I have many possible interchangeable variables in the model, I was wondering how to apply the Focused ...
0
votes
0answers
10 views

R Packages for rank-preserving structural failure time model (RPSTM)

I have a randomized clinical trial data that has high percentage(30-40% in both arms) switching over to a different treatment regimen. By browsing through some literature, I am inclined to perform ...
0
votes
0answers
7 views

Heterogeneity test for risk factor association (hazard ratio/coefficient) in two or more different survival outcomes

Suppose I'm interested in comparing smoking category (current, ex, non-smoker) as a risk factor in two or more different but similar (considerably exclusive) outcomes, say lung cancer of different ...
0
votes
1answer
59 views

Calculating Sample Size for Non-Inferiority Test in Cox Proportional Hazards Regression With Stratification

I have a binary predictor, X, in a Cox proportional hazards regression model, and I want to show that it is NOT a significant predictor. In other words, I want to show that there is not a significant ...
2
votes
1answer
43 views

Determining sample size for proportional hazard

I am in the design phase for a longitudinal study examining the effect of a predictor (neighborhood risk score) on time to an outcome (re-arrest), as well as whether or not the variation explained by ...
0
votes
1answer
90 views

Odds ratio of a continuous variable (univariate cox proportional hazards), how to plot that variable against death%?

I have a continuous variable X with which i ran Cox proportional hazards. The outcome was 1=Death, 0=censored/still alive. I have an odds ratio 0.516 for this predictor. 1) How do i interpret that ...
1
vote
2answers
28 views

What estimator to use in Cox model

I am using R/survival to analyze survival data from cancer patients. I have recently learned that there are many kinds of estimators for the Cox model, and I understand, that in theory, their order of ...
4
votes
1answer
166 views

A peer-reviewer wants more complex statistical modeling - is it reasonable?

I've submitted a manuscript to a journal and the associate editor wrote that his readers will want to know more about how the predictor of main interest (occupation) is related to death, and this will ...
0
votes
0answers
61 views

Overfitted Cox regression

I'm trying to compare the prediction abilities for death of two new biomarkers using a cohort of 173 patients. My problem is that I have only 31 outcomes and my baseline model (the one without any ...
0
votes
0answers
16 views

Cox Regression Analysis

I am trying to model the inter-arrival time between events as a survival model that depends on a set of covariates. So, I treat each event as a "death" in my model and therefore, calculate the ...
1
vote
1answer
69 views

Interpretation of interaction between covariates and time in cox regression

If I have a categorial variable (let's say $X$) and a continuos variable (let's say $Y$). IF I fitted a standard cox model, it will result in a violation of the constant HR over time (based of ...
3
votes
0answers
108 views

Is there a way to model left truncated and interval censored data in R or SAS?

We have a study where our participant underwent some surgery at time = 0, but at various ages. Our follow-up is based only on Medicare age-eligible people, so we have to wait until they reach the age ...
2
votes
1answer
73 views

Average hazard rate with Cox proportional hazard model always larger than the hazard rate without any explanatory variables?

I am estimating a Cox proportional hazard model with and without explanatory variables. Without explanatory variables, the hazard rate is just the proportion of all individuals that failed at time ...
1
vote
1answer
30 views

Is Cox PH model still applicable when proportional assumption is violated for treatment effect?

I am using Cox proportional hazard model to compare the survival of two groups (treatment vs control) of patients. However, hazard rates were not proportional between the groups. Now, would it make ...
1
vote
1answer
52 views

Extrapolating the effect of covariable changes in Cox proportional hazards models

I have a Cox proportional hazards model in R (see made-up example below) that models the effect of some variable, say weight. From this model, I'd like to extrapolate what a change in weight from say ...
0
votes
1answer
61 views

Interpretation of Cox regression with time varying covariates

After fitting my model to a time varying cox regression, let's say I have a continuos variable $ X $. The hazard ratio of this variable will be higher than 1 (about 2 and it is significantly ...
0
votes
0answers
30 views

Can the rcorrp.cens paired concordance test be done taking into account strata?

Followup to these discussions: Bootstrapping Hmisc::rcorrp.cens for paired concordance? Stratified concordance index (survival::survConcordance) Is there a way to perform a stratified paired ...
4
votes
1answer
265 views

How to create a toy survival (time to event) data with right censoring

I wish to create a toy survival (time to event) data which is right censored and follows some distribution with proportional hazards and constant baseline hazard. I created the data as follows, but I ...
0
votes
1answer
70 views

AIC or BIC for model selection in Cox regression (SPSS)

Does anyone know if there is a method (a macro) to calculate AIC or BIC for a model in Cox regression using SPSS?
1
vote
1answer
32 views

Stratified concordance index (survival::survConcordance)

What is the idea of having a stratified concordance (C-index) in survival::survConcordance, as opposed to computing the concordance over all samples ignoring the strata? Can there be some inflation ...
0
votes
0answers
17 views

Is the magnitude of the hazard ratio change reflective of survival function change?

I need to know the change in survival caused by increasing inbreeding in my study group. As my model has random effects, and as coxme has no easy ...
1
vote
1answer
72 views

How to conduct Cox PH stratisified by matched pair in R

I am wanting to calculate hazard ratio in a matched cohort design. For such I am using the coxph() function in R. But I have been recommended to stratify by matched ...
3
votes
0answers
39 views

heteroskedasticity in logit/cox

I am using a logit and a cox proportional hazard model for my analysis, and the newest version of Stata. I have found that there are no tests to check for heteroskedasticity for logit/probit models, ...
2
votes
1answer
64 views

Interpreting output of Cox regression model

I am trying to use two variables - activity score (ascore - a whole number indicating amount of activity) and gini (given by Gini-Simpson index - a value ranging between 0 and 1, indicating diversity ...
1
vote
0answers
45 views

How can the output from a Cox proportional hazards model be mathematically translated into a log regression model? [closed]

I would like to write down the log-regression model associated with the formula: coxph(Surv(time, status) ~ rx + cluster(litter), rats) I am not interested in ...
0
votes
1answer
42 views

Study design - fresh look!

Need to be advised outside of the circle. I am more a physiologist+mathematician plus-c,c++,java coder/developer. Chart data. From year 2001 till 2012. 89 nursing stations or emergency call ...
0
votes
0answers
11 views

Change in destribution af variable with time - doing cox regression

A hopefully a question that has a simple answer:) I'm doing cox regression on a large dataset. Event=death. Destribution of the main variable change a lot during the timespand (10years) - i.e type of ...
1
vote
0answers
37 views

calculus of predicted number of failures in cox regression

Suppose we rank the prognosis index (the linear product beta*X) of the individuals in a Cox regression and divide this set in a number G of groups. It is trivial to count the number of observed ...
0
votes
2answers
49 views

how to deal with dependence/interaction among covariates in a cox regression model

In case of a linear regression, if we are to account for interaction between two regressors x1 and x2, we write a model like ...
1
vote
1answer
99 views

Is oversampling done for Cox regression data?

I have a dataset consisting of about 48000 people, about 40,000 of which die before the end of the study and get a failed = 1 and the remaining 8000 have a failed = 0 because they're either lost to ...
0
votes
0answers
47 views

Cox PH model - Time-independent vs time-dependent covariates

I am trying to fit two different Cox PH models to some data I have, and get strange results when I consider the same variable as time-independent as opposed to when I consider it time-dependent. More ...
5
votes
1answer
131 views

Cox discrete time regression model question

Cox's 1972 publication Regression Models and Life Tables links logistic regression to an extension of the discrete time proportional hazard model. I do not understand how Equation (21) in the ...