This is the first English book on Project Comparison Technique, i.e. comparative project prognoses, project theory, project evaluation, and project benchmarking in all branches. It facilitates the first steps towards project comparisons for project management experts and scientists, details possible approaches and relates real-world experiences. While readers are assumed to have some knowledge of project management, the mathematical and statistical aspects are explained. For the first time in the history of project management we show that the efficiency of project realizations can be evaluated objectively and numerically in detail and as a whole, and how to do so. We lay out the first comprehensive, scientifically founded characteristics system for projects, formulate the first mathematical project model, demonstrate the usefulness of the characteristics system with authentic projects, and show how to handle the new tools and how to present them in tables and diagrams.