Abstract : We present in this thesis a method to assess a system efficiency based on modelling of the temporal and stochastic spread of faults. The OEE (Overall Equipment Effectiveness) has become through the NF E60-182 standard one of the major indicators of the effectiveness in piloting production systems. It includes 3 main concepts (Quality, Performance and Availability). If its evaluation can be easy for a single system, the modeling of its components for the global efficiency assessment is much more difficult (taking into account redundancies, temporal scale factors…).in order to take in account the local contribution of each component of complex production system, a notion of OTE (Overall Throughput Effectiveness) is developed. The purpose of OTE is twofold: it measures factory-level performance and factory-level diagnostics such as bottleneck detection. The expected result gives a formal contribution to establishment a methodology for analysis, design, and decision-making. The results are discussed using a demonstrator based on AltaRica Data-Flow, language in both formal and graphic and real tool modeling / simulation.