We theoretically evaluate the prediction efficiency of the overlapped block motion compensation (OBMC) compared with the conventional non-overlapped approach. Based on the one-dimensional signal model characterized by the AR(1) process and first-order polynomial motion, a condition under which the performance of the OBMC is better, and an optimum window function are derived. From the results, we discuss and analyze several properties of the OBMC, some of which have been experimentally reported in the literature.