Preservation coefficient

For the sake of clarity, we have chosen to apply a preservation coefficient based on the phone renewal rate. This is a strong assumption, as it is not certain that the rate of renewal of the telephone is correlated with that of other devices, especially as the telephone is often "the worst pupil".

We assume that people who say they often renew their phones keep them for half their average lifespan, and that people who keep their phones for as long as possible extend their average lifespan. This grid may evolve if new sources or studies are added.