Kaplan meier curves are usually calculated for survival probabilities over time. Is it valid to calculate kaplan meier curves for survival probabilities over other continuous variables e.g. over height, over levels of a biomarker? Thanks
The thing about time is you experience each value of it, and death/failure (or whatever other one-off event is considered) is a risk at each point.
With levels of a biomarker you're presumably not experiencing each lower level between 0 and the current value along the way to experiencing the current value.
If you mean to follow single individuals over time, you could perhaps substitute height for age, at least up to the point where height no longer changes.
Similarly one might consider length along a wire to the first fault.