Questions tagged [accelerated-failure-time]

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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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1answer
21 views

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 ...
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12 views

What is the distribution of response, if the error distribution is non-normal?

Consider the AFT model: $Y=log(T)=\beta^T x + \epsilon=\mu + \epsilon$ ; where $\epsilon \sim Gumbel(\alpha, \beta)$. What should be the distribution of $Y$? Is it $Y \sim Gumbel(\mu+\alpha, \beta)$?
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39 views

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 $S_0$ ...
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31 views

Implementing logistic regression model in prediction model - use outcome or probability?

My question deals with the principles or way of thinking about implementing a logistic regression model in a larger scale forward prediction. Let's say I have a trained logistic model which can ...
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20 views

Proof of the hazard of the AFT model

This is an attempt to prove the hazard function $h$ of the accelerated failure time model as presented by Klein and Moeschberger in "Survival Analysis: Techniques for Censored and Truncated Data,&...
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1answer
106 views

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 ...
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1answer
16 views

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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2answers
27 views

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 $...
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99 views

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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41 views

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 ...