What is a Pareto Chart?
A Pareto chart is a bar chart of problem causes sorted from most to least frequent, usually with a cumulative-percentage line. It operationalizes the 80/20 rule: a vital few causes produce most of the pain, so fix those first.
Its job is focus. Teams facing forty defect categories don't need forty initiatives; they need to see that three categories cause three-quarters of the trouble. On the exam: Pareto = prioritizing causes by frequency; fishbone = finding the root cause of one problem.
Worked example
A support team logs 500 tickets by cause: password resets (210), sync failures (140), billing confusion (75), everything else (75). The Pareto chart makes the decision for them — self-service password reset and a sync fix address 70% of all volume. The other 37 categories can wait.