The task of data evaluation is to develop mathematical-statistical models, estimation methods, and algorithms to derive the best possible estimates for unknown parameters from observations that are subject to deviations (errors), to provide a consistent system of estimated (balanced) quantities, and to offer accuracy estimates for observations and derived quantities. This work presents not only the fundamentals but also the procedures and methods of data evaluation. Given the wide range of specialized methods, the authors do not aim to cover the entire spectrum but instead focus on methods that have broad applicability. The book is suitable for both independent study of the methods of scientific data analysis and as a companion text.