There are seven basic quality tools that organizations can utilize for quality management as per the Project Management Body of Knowledge (PMBOK), 6th Edition. The same tools are applicable to the Six Sigma Define, Measure, Analyze, Improve and Control processes commonly referred to as DMAIC. Below is a description of each of the seven basic quality tools and how they are applicable to the DMAIC methodology.
Cause and effect diagram
Also commonly referred to as the Ishikawa or Fishbone diagram, the tool is used to help identify the possible causes of a specific problem and can also be used hand-in-hand with brainstorming. It shows the relationship between the problems and the influencing factors, thus it is essential for root cause analyses.
Analyze – The Ishikawa diagram can be used during the Analyze phase to classify root causes in order to simplify prioritization and to better assess them.
A flow chart provides a view of how a company’s workflows can be used to initiate process improvement activities. A flow chart is created using standard symbols and shows the sequence of tasks performed and their relationship in a graphical format.
Define – This phase can be used to understand the process and provide insight into the causes of inefficiency and frustration so that improvements can be made.
Measure – Flow charts created during the Define phase are reviewed and additional information can be added to make them more comprehensive.
Analyze – An analysis of the process map can reveal some fairly obvious sources of inefficiency and delays in the process.
Improve – A flowchart can be created for the new process that will be followed as a result of the improvements being implemented.
Control – The process map, created during the Improve phase, must be fully analyzed and updated in order to reflect any changes resulting from a roll out.
A Pareto chart is based on the Pareto principle, also known as the 80-20 rule or rule of the vital few, which states that a small number of causes (20%) are responsible for a large percentage (80%) of the effects. The graphical display in a Pareto chart is used to display the types of problems that affect a process and their relative significance.
Define – The define phase can be used to decide which problems can be addressed first as part of a six sigma project.
Improve – This phase can be used to identify where the team should focus their continuous improvement efforts.
A Histogram is a bar graph that shows data in columns that vary in height depending on the frequency of the occurrence of the data values. It can be used for the visual representation of data collected from other tools – such as check sheets – hence making it easier to interpret where the problems are coming.
Analyze – Can be used to identify variance in the process parameters, as well as predict future process performance.
A check sheet is a simple tool that can be used to record information in real time at a particular location over a period of time. The frequency of problems and defects associated with a particular system can be recorded on a check sheet and can be used to create cause and effect diagrams, Pareto diagrams, scatter diagrams etc.
Measure – The frequency of data for the items being measured is collected to perform further analysis.
A scatter diagram is used to display the values of two variables of a set of data and to make predictions based on the data. It consists of a horizontal axis (X-axis) and a vertical axis (Y-axis) and a series of dots representing the individual X and Y axis values. A scatter diagram allows the identification of possible relationships between two different sets of variables. This, therefore, can be used to display the correlation.
Analyze – Can be used during the Analyze phase to classify root causes in order to simplify prioritization and to better assess them.
A control chart is a statistical tool that differentiates process variations as a result of known causes, and variations resulting from unique causes through a graphical display. In a control chart, control limits can be used to monitor process variation so as to come up with the necessary corrective action.
Measure – Determination of which components of variation are inherent in the process (common cause) and which are due to external or specific factors (special cause).
Control – The chart is updated regularly, enabling the process owner to monitor process shifts or any other signs that identify process performance issues.
Improve – Often employed to show the reduction in variations and improvement in performance.
The key to determining which tools are most useful is understanding the impact of any issues and which of the tools is most likely to help clearly uncover the root cause and fully resolve issues.
Tapera Mangezi, PMP, PMI-PBA, SMC, is the founder and director of Proximate Academy, a project management training and consultancy company. He is also a certified senior SAP plant maintenance consultant and project management consultant with many years of experience in working on various projects within the utilities, energy, and public sectors, and the manufacturing, logistics, facilities, and mining industries. Tapera has a strong engineering background and also holds various other certifications. He is currently working towards his MSc in Business Management with a specialization in Project Management at the Edinburgh Napier University. Tapera writes about business analysis and business processes.