The theory of multirate signal processing has witnessed a great deal of progress since the publication of the first textbook by Ronald E. Crochiere and Lawrence R. Rabiner in 1983. However, this progress has been mainly in the area of deterministic systems with perfect reconstruction and orthogonal constraints. This book introduces a statistical theory for extracting information from signals with different sampling rates. This new theory generalizes the deterministic theory of multirate systems beyond many of its constraints. Furthermore, it allows for the formulation and solution of several new problems including multirate spectrum estimation, multirate time-delay estimation and multirate sensor fusion. The author presents background material, key principles, potential applications and leading-edge research while striking the appropriate balance between clarity and brevity. The book is self-contained and provides a valuable resource for signal processing researchers, graduate students and practicing engineers.