[R] Kaplan Meier - not for dates

[Polwart Calum (COUNTY DURHAM AND DARLINGTON NHS FOUNDATION TRUST)]

>  2. The answer will be wrong.  The reason is that the censoring occurs on a time scale, not a $ scale: you don't stop observing someone because
> total cost hits a threshold, but because calendar time does.  The KM routines assume that the censoring process and the event process are on the > same scale.
> The result can be an overestimation of cost.  See Dan-Yu Lin, Biometrics 1997, "Estimating medical costs from incomplete follow-up data".
>
> Terry Therneau

Thanks that's extremely useful.

I'll dig out that reference.

You are correct my censoring is happening on an event - (dis)continuation of treatment - not on reaching a cumulative cost.

Calum





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