Estimating the reduction time of quantum states

An effective description of microscopic measurements is given, in which the precise moment of probing is not determined. Within this scenario we propose a scheme that relies on an "attempt" to make a forbidden simultaneous measurement of two incompatible observables. Although bound to failure in what concerns this goal, the process can lead to information on a possible non-vanishing time scale $\delta t$ involved in the collapsing of the wave function, even if the duration $\Delta t$ of the individual measurements is much larger than $\delta t$.