This text uses a series of empirical examples, such as the re-organization of production in a ski-manufacturing firm from a classical taylorist to an autonomous team-based organization. It proposes to apply Harvey Leibenstein's economic theory of "X-factor" of production to analyze productivity gains in such situations. The X-factor is an "epistemological residue" which appears when theory and practice try to reduce the concrete human activity, a complex and heterogeneous system, to the scientific and technological discourse which claims to account for activity and make it controllable. The history of Economics and Management Science clearly shows how and when a functional definition of activity was adopted and implemented, rather than a cognitive definition. However there is an alternate option, defended, for instance, by Wittgenstein and Dewey, quite coherent with Leibenstein's "factor-X" theory: no rational discourse can give a complete, deterministic and predictive account of activity and its learning effects, with several implications: 1) activity cannot be modelled in a predictive and controllable way by an external observer, though most human resource management tools and management control tools are based upon the opposite idea, 2) the failure of most activity control attempts raises the issue of activity autonomy, actor's autonomy and action process autonomy, 3) the acceptance of activity autonomy paves the way for the development and implementation of new, cross-functional management methods.
LORINO, P. and PEYROLLE, J.C. (1999). Enquête sur le facteur X. L'autonomie de l'activité pour le management des ressources humaines et pour le contrôle de gestion. ESSEC Business School.