This book includes methodological foundations as well as several empirical applications of the novel method for the decomposition of market shares developed by the author. Philipp Brüggemann demonstrates, using the example of market shares of national brands and private labels as well as retail chains, how previous market share analyses can be improved through decomposition by regular and promotional prices. The method is characterized by its high transferability to various questions in both academic and practical contexts. This innovative method can be applied not only to market share analysis but also to numerous other relative and absolute key performance indicators. Using regression analysis or structural equation modeling, this method can be used to break down causal relationships between independent and dependent variables into components.