The previous chapter motivated the need for a precision measure and enumerated a list of requirements that the measure should satisfy. This chapter presents the procedure to measure precision, both an intuitive explanation as well as a complete formalization based on the definitions of Chapter 3. The procedure is based on detecting and pinpointing escaping arcs, i.e., the parts where the model allows more behavior than the one observed in the log. This basic procedure analyses the model as a whole (i.e., monolithic analysis). Later chapters consider variants and extensions of the procedure regarding both its input and its output.