A list of some of theories, tools, and tactics used to improve processes and performance of an organization or system: Lean, Six Sigma, HPT, Continuous Improvement, Agile, SPC, Kaizen, Scrum, Just-in-Time, etc. The common thread of these is to 'increase quality' and 'decrease waste'- both typically defined and measured as they impact the financial health of an organization.
When I'm working on improving a process, the most interesting 'tools' are those that help me understand the whole system. In addition to data analysis, I want to understand the value and influence of human psychology and behavior. I'm excited by what makes teams successful, what keeps employees invested in innovation and improvement, and how their leaders help or hinder motivation, creativity and engagement. Measurement, statistics, and data are important details and can tell you part of the story. But it's a compelling story and I want to read it from cover to cover!