1. Cause-and-effect diagram which is also called the Fishbone diagram and
    Ishikawa diagram: used to determine the root cause of problems or defects by
  2. Flow charts or process maps: used to display the flow of steps.
  3. Check sheets: used as checklist when collecting information and to prevent
    problems from happening.
  4. Pareto diagrams: used as a quick identification of problems.
  5. Histograms: used to give visual effects for different data.
  6. Control charts: used as evaluation tool to check if the system is under
    control or not.
  7. Scatter diagrams: used as research or study tool allows to give two different
    quantities and study the relation between them.