CK030 - Accelerated Failure Time Model Flashcards
1
Q
What is the formula of the ‘accelerated failure time (AFT) model’ ?
A
log(T) = b0 + b1x1 + b2x2 + …
2
Q
What are the assumptions of the ‘AFT model’ ?
A
- Linearity
- Additivity
- Error terms distribution
3
Q
What is the most important assumption for the ‘AFT model’ ?
A
The error terms distribution
4
Q
What is the interpretation of the coefficients in an ‘AFT model’ ?
A
A 1 unit increase in x corresponds to:
- A b change in the average log(T)
- Multiplies average T by a factor of exp(b)
5
Q
How to check for the ‘error terms distribution’ ?
A
Compare the Kaplan-Meier curve of the residuals (so residuals instead of time) and compare this to the Kaplan-Meier curve of the error terms (so from the assumed distribution)
