All Questions
Tagged with cox-model weibull-distribution
28 questions
1
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1
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156
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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
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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
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1
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63
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2
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2
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92
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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
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1
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235
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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
0
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1
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493
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Calculate survival function for remaining life prediction using CoxTimeVaryingFitter in Python
Cox’s time-varying hazard model is given here which is "CoxTimeVaryingFitter"
The mathematical formulation is represented as:
The values of log partial hazards "(x−x¯)′β" are ...
- 151
1
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1
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326
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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
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1
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125
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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
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1
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716
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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
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1
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2k
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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
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1
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343
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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
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1
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184
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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
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0
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102
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Schoenfeld residuals - theoretical question
I have a doubt about the Schoenfeld residuals that are used to check the Cox proportional hazard model.
The residuals formula is:
$$\hat{r}_{ik}=c_i(x_{ik}-\hat{\bar{x}}_{w_ik})$$
$$\hat{\bar{x}}_{...
- 46
0
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1
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4k
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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
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1
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960
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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
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2
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14k
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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
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0
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579
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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
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0
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37
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Which variables in the models below meet acceptable thresholds for accuracy, also, which model is more statically accurate
Which variables are most significant?
...
0
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1
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212
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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
0
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1
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1k
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SAS Proc lifereg phreg and lifetest - survival plot
I have to draw a survival probability plot with three different surviuval estimates using the phreg, lifereg and the lifetest procedure with sas for make a confrontation
the models:
...
- 75
4
votes
1
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1k
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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
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0
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47
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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
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3
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6k
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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
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1
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490
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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
0
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0
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757
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How to simulate informative censoring in a Cox PH model?
I wish to simulate events from a Cox PH model where the censoring is informative, and to compare parameter estimator quality with estimates obtained from data generated by a Cox PH model with non-...
- 728
2
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0
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132
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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
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1
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1k
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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
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1
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5k
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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 ...
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