[Innovation and obsolescence (author's transl)].

The economists analyse the facts of our everyday--or professional life to insert management--or anticipation rules from them. The progress of innovations and their obsolescence fall within these studies. Recent works have shown that the spreading of innovations in the medical fields was practically identical to that in the industrial field, and that its function in relation to time was written under the form of: P = K divided by 1 + e-(a+bt) P representing the proportion of departments which adopted an innovation at the time t, K representing the proportion of those which will adopt this innovation (a and b are constants). The derivated coefficient in relation to t, that is to say the variation of the proportion of departments adopting innovations in relation to time, measures the speed of diffusion of this innovation (Louise B. Russel, 1977). But can this equation be applied in the field of health, to organisational innovations as well as to those which have a material, therefore industrial support? On the other hand do techniques and equipments become obsolete simultaneously? Finally does the public or the private hospital slow down or speed up the appearance of innovations and their obsolescence? Such are the problems we will endeavour to set... before being able to solve them.