!! Background The development of large [knowledge bases|Doc ] is a long-term process that requires careful quality management. A very important method of quality management is the analysis of key performance indicators. For a knowledge base a number of indicators (variables) is identified and their outcomes and values are checked over a number of real life or at least realistic cases. The performance of the knowledge base can then be analyzed over a big data sample, for example by comparing the averages of the indicators with expected or desired values.