Questions tagged [accelerated-failure-time]
The accelerated-failure-time tag has no usage guidance.
18
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How to predict survival curves with step changes over time
I'm trying to predict the survival curves for customers, knowing that for some rare customers after a certain time the survival probability has a jump. Those jumps are due to endings of minimum ...
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What is the model for dist="logistic" in R survreg, and in what unit are the coefficients?
Does anyone know the model and parameterization for surveg with dist="logistic"? I'm having trouble finding documentation anywhere. I checked Chapter 2.2 of Kalbfleisch and Prentice and only ...
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Xgboost AFT model predicts infinity
I used Xgboost AFT model to predict survival time but get some infinity predictions. Is it normal? How should I interpret that?
I changed aft_loss_distribution from 'normal' to 'logistic', then had ...
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Simulate a Weibull regression model
I am trying to simulate a AFT Weibull model in R using a log-linear model
\begin{align}
log(Y)=\beta_0 +\beta_1 X1+\beta_2 X2+c W
\end{align}
where $W ~$ a extreme value distribution. below is my ...
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Know how to choose appropriate distribution for AFT
It is written in many web resources that the distribution of the accelerated failure time model must be specified correctly but I don't think I've seen anything about how to know this.
I see often ...
- 345
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Relationship between Survival Distributions and Log Linear Regression in Accelerated Failure Time models
The accelerated failure time model (AFT) can be expressed as:
$S_{1}(t) = S_{0}(\frac{t}{\gamma})$ where $S_{0}$ is a specified baseline survival distribution and $\frac{1}{\gamma}$ is the accelerant/...
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How to formulate and simulate data from an accelerated failure time model?
I understand that an accelerated failure time model can be conceptualized as a cox model which includes covariates whose effects depend on actual time, so the convenient expression of the partial ...
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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 ...
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628
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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 ...
- 325
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Weibull and Lognormal Fits
I have simulated failure time data for some components.
I tested whether a Weibull or lognormal distribution best fit the data. Please see Figures below. The figures provide median and $95\%$ ...
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139
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Recurrent event data modelling - Cox PH or AFT?
I am attempting to model recurrent event data in Stata. My data is dataset of patient records and I am modelling a patients first delivery of a mobility aid and the subsequent deliveries of new ...
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flexsurvreg log logistic intercept in R
I'm trying to fit a log-logistic AFT model with flexsurvreg(). With AFT model,
$$\log T = \gamma_0 + \gamma_1 z_1 + \gamma_2 z_2 + \sigma W,$$ where W ~ standard logistic distribution.
Below is an ...
nens
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543
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Finding a distribution of Accelerated Failure Model
Can someone please answer these 3 questions related to AFT model?
In Accelerated Failure Time (AFT) model, $S(t│β,x)=S_0 (exp(β^T x).t)$, where $S_0$ is the baseline survival function, does $S_0$ ...
- 135
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AFT models in Stata with time-varying covariates
The AFT models from Stata's streg can handle time-varying covaraites. In particular, the manual states that
streg is suitable ...
- 2,356
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AFT model with varying production
I want to implement an AFT model to study the failure time of a product given it's width.
$$S(t|width)=S_0((\beta_0+\beta_1 \times width)t)$$
However the prodction has varied during the time (less ...
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Scale Parameter in a Log-Linear Accelerated Failure Time Model
Let the logarithm of the random varible $T_i$, associated with the lifetime of the $i$th individual in a survival study, follow the disitribution
$$log(T_i) = \mu + X_i\beta + \sigma\epsilon_i$$
with $...
- 503
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D-Calibration for Survival Models with imbalanced outcomes
I am building an accelerated time failure (AFT) model on a highly imbalanced data set 90% survival 10% death. I understand that we can not use Brier score because of the outcome imbalance, Brier score ...
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Assumptions of an Accelerated Failure Time model?
I have an AFT model, comparing the adjusted survival of 5 groups and seeming to give reasonable results. As I do not feel confident in survival modelling, does this model has assumptions that need to ...
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