The two existent balance‐equation methods for electron transport, which incorporate Bragg scattering and give rise to bulk negative differential mobility, are further investigated using the Boltzmann transport equation for Bloch electrons. We point out that the ansatz employed in the earlier Bu¨ttiker–Thomas (BT) scheme to relate the average drift velocity and the average momentum, should be modified for a general energy band. Numerical calculation of superlattice miniband conduction shows that the modified BT force‐balance method yields a velocity–field behavior almost equivalent to that predicted by the acceleration‐balance method of Lei, if the appropriate momentum function is used in the calculation of the BT frictional force, such that Bragg scattering is properly taken into account in the process of electron scattering. ©1996 American Institute of Physics.