# 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 production at the beginning of the commercialisation of the product). Is it problematic ? And is there anyway to fix this problem by adding a variable in the model ?

• When you say production varied, are you referring to the total number of products created? Did anything change about the relationship between failure time and width?
– Eli
May 6 '21 at 13:36
• Yes it is the total number of products created. But the relationship between failure time and width keep unchanged May 7 '21 at 5:57