A method to simultaneously determine both the wall-motion speed and the nucleation probability of magnetic films is presented, where the domain reversal patterns are modelized by time-dependent circular domains formed by the nucleation process and then, expanded by the wall-motion process. The present method has been applied to understand the contrasting reversal behaviors in the Co/Pd multilayered system and the difference in the nucleation probabilities of the samples was found to be a major origin for the observed contrasting behaviors in this system. ©1997 American Institute of Physics.