All Questions
23 questions
1
vote
1
answer
156
views
Capture time variation in survival analysis
I am currently working with intraday time-to-event data, where the time to event typically spans just a few minutes. I want to compare the survival curves of two subpopulations in my sample.
The ...
- 363
2
votes
1
answer
545
views
DIfference between hazard ratio and partial hazard in survival analysis
The hazard function in survival analysis is represented as (https://in.mathworks.com/help/stats/cox-proportional-hazard-regression.html):
Here the exponential term is termed as hazard ratio as ...
- 151
1
vote
1
answer
63
views
2
votes
2
answers
93
views
Is this an adequate example for simulation and modeling uncertainty in survival and hazard curve estimates?
I'm studying simulation and in particular uncertainty in survival curve estimates, by drawing from a distribution of parameters (for the Weibull distribution), using the variance-covariance matrix ...
- 827
0
votes
1
answer
235
views
Obtain the survival function plot by building an overall survival regression model
I need to build an overall survival regression model that can show the survival plots for id's with multiple rows.
I have used the Weibull function to define the baseline hazard function h0(t) and Cox ...
- 151
1
vote
1
answer
326
views
Calcuate the coefficients of time varying covariates in Cox hazard model
The cox time varying covariates (x(t)) model is as such:
The above formulation can be seen here: https://lifelines.readthedocs.io/en/latest/fitters/regression/CoxTimeVaryingFitter.html
Here, can ...
- 151
2
votes
1
answer
125
views
Extended Weibull-Cox model survival function
I'm reading an article where the authors use an extended Cox-Weibull hazard model with time-varying covariates to model survival time of an individual. This individual is allowed to start at week $m$, ...
- 439
0
votes
1
answer
716
views
What is the meaning of the flexsurvreg plot and its res.t?
I use the flexsurverg to estimate the a Weibull survival model with a time varied covariate, where “utility” is a continuous function, and the result is shown as follows:
I plot the fit function and ...
- 57
2
votes
1
answer
2k
views
AFT model interpretation
I am slightly confused about the way accelerated failure time models work in comparison to proportional hazard models.
Is it a correct statement that while the PH model assumes covariates multiply ...
- 555
2
votes
1
answer
343
views
Weibull Proportional Hazard in pymc
I’m looking to create a Bayesian proportional hazard model where the baseline hazard is modeled by a Weibull distribution (or some similar continuous distribution).
I’ve reviewed (and implemented) the ...
- 103
4
votes
1
answer
184
views
Is a radioactive process describable by survival analysis?
According to this source, the survival function is defined as
$ S(t) = e^{- \lambda \cdot t} $
while, according to this source, the number at time $ t $ of radioactive atoms is
$ N(t) = N_0 \cdot e^{- ...
- 3,493
0
votes
1
answer
4k
views
How to simulate survival data with censoring using R
I want to simulate survival data with a sample size of N=100, which follows the Weibull distribution with proportional hazards and constant baseline hazard. Two correlated covariates, which follow ...
- 87
3
votes
1
answer
960
views
How to interpret coefficients from weibull regression for variables of proportion?
I want to fit a weibull regression model. The variables are however given as proportions (i.e. they are in interval <0,1> ... is this compositional data if they do not sum up to 1?). An example ...
- 753
4
votes
2
answers
14k
views
How to model survival analysis when proportional hazards assumption is not met and stratification and time-varying are not possible?
I am modelling a survival analysis over a rather long follow-up period (10 years). My exposure is time-invariant and clearly violates the proportional hazards assumptions so Cox Proportional Hazards ...
- 313
4
votes
0
answers
579
views
How can I compare parametric and semiparametric survival models?
On a given dataset, I am running a semiprametric Cox proportional hazards model, together with a series of parametric models (Weibul, gamma, lognormal, exponential, etc.).
How can I know which is ...
- 241
0
votes
1
answer
212
views
Predicting survival time from log-hazard
I have estimated a Weibull regression model in BUGS/JAGS which gives me the log-hazard as a function of intercept (baseline hazard) and covariate effects.
The intercept is estimated as -9.826 and one ...
- 215
4
votes
1
answer
1k
views
Proportional hazards assumption Cox's model vs AFT
I'm modelling survival data with Cox's model and AFT model (weibull) with only treatment as dependent variable.
From the KM plot of the survival probability i saw that there isn’t a different trend by ...
- 75
1
vote
0
answers
47
views
Survival analysis without a direct coupling between subjects and events
I am studying the failure rates of some components. The data that we possess are atypical for a survival analysis, however. The population and year of installation of components are known for the last ...
- 26
8
votes
3
answers
6k
views
Weibull Survival Model with Time Varying Covariates in R
I am trying to run a survival model using the Weibull approach, but the wrinkle is that I have time-varying covariates. I am using the survival package in R. My call is:
...
- 81
2
votes
1
answer
490
views
Need help to simulate Survival Times with a time-varying Covariate
I would really appreciate if someone can help me figure this out as I have been working on it for few days now and I don't know what I'm missing that it's not working. Basically, my goal is to sample ...
- 2,204
2
votes
0
answers
132
views
Variable effect in Weibull and Cox models
Is it possible to compare effect of variable on the survival time in the Cox model and in the Weibull regression model?
- 531
6
votes
1
answer
1k
views
How would you visualize the difference between Cox/Weibull regression?
I'm trying to figure a way of properly displaying the difference\resemblance between various regression values on the same data set, using cox ph, weibull regression and log-normal regression.
...
- 531
4
votes
1
answer
5k
views
Why do coxph() and survreg(, dist="exponential") NOT return the same coefficient (except for expected opposite sign) in R?
If I understand correctly, the coefficient of a covariate X under a Weibull accelerated failure time (AFT) model is related to the ...
- 101