The robust stabilization of a family of stochastic plants described by interval ARMAX models is here considered. The solution proposed is given by a linear, time-varying compensator and by a supervisor. The compensator may assume a finite number of different, possible configurations, at least one of the which stabilizes the actual unknown ARMAX model. The task of the supervisor is to determine the switching instants of a scanning among the elements of the family, according to a suitably defined experimental test on the model output. The switching is stopped when the stabilizing configuration is attained.