Some remarks on failure-times, surrogate markers, degradation, wear, and the quality of life.
Suppose that data are available on failure-times and on a time-evolving process on each individual, called in some contexts wear or degradation. Four rather different types of relation between such a process and failure are described and brief comments on appropriate analysis sketched.
Cox
D R
DR
Nuffield College, Oxford. David.Cox@nuf.ox.ac.uk
D000704:Analysis of Variance; D006304:Health Status; D006801:Humans; D015233:Models, Statistical; D011788:Quality of Life; D013269:Stochastic Processes