"Statistical mechanics deals with the description of physical phenomena in terms of the stochastic behavior of large numbers of components, such as atoms or molecules, especially regarding the distribution of energy among them. Statistical mechanics provides exact methods to connect thermodynamic quantities to microscopic behavior. Thus, measurement in quantum mechanics is usually a rough procedure that destroys many properties of the system. This is obvious from the Hilbert space construction, as in the language of Hilbert spaces; measurement conducted on the system destroys the quantum superposition reassembling the probability of detecting a particular state of that system. However, the notion of weak or gentle measurement came quiet recently into the study of quantum mechanics. Statistical Mechanics is intended to present state of the art on the behavior of macroscopic systems by studying the statistical properties of their microscopic constituents. This book is a guide to the practical application of statistics in data analysis as typically encountered in the physical sciences, and in particular in high energy particle physics. Statistical methods are invariably needed, however, in order to extract meaningful information from experimental data. A new approach to classical statistical mechanics is presented; based on a new method of specifying the possible states of the systems of a statistical assembly and on the relative frequency interpretation of probability. "