In TCV, L-mode to H-mode transitions have been observed in a wide variety of plasma configurations. Two statistical methods, discriminant analysis and a nonlinear system identification, have been used to localize the boundary between the L-mode and H-mode domains in the multidimensional operational space. For control purposes, an estimate of the shortest distance between the actual position in the operational domain and the boundary is defined, and the parameters to modify in order to reach the transition are identified.