According to the PMI Guide to Business Analysis, a Pareto analysis is a tool that helps to prioritize problems or causes based on their frequency or impact. It is based on the Pareto principle, which states that 80% of the effects come from 20% of the causes. A Pareto analysis can help to identify the high-priority changes needed to improve a service by showing which problems or causes account for most of the complaints or dissatisfaction. A work breakdown structure analysis, a flowchart, and a cause-and-effect diagram are other tools that can help to analyze a service, but they do not necessarily help to prioritize the changes needed to improve it.Reference: PMI Guide to Business Analysis, page 145-146.