Japan is known worldwide for its quality products and services. One of the many reasons for this is its excellent quality management. How did it become so? Japan has Dr. Kaoru Ishikawa to thank for that.
Postwar Japan underwent a major quality revolution. Companies were focused on training their employees in statistical quality control. But soon they realized that the complexity of the subject itself could intimidate most of the workers; so they wanted more basic tools.
Dr. Kaoru Ishikawa, a member of the Japanese Union of Scientists and Engineers (JUSE), took it to his hands to make quality control easier for everyone – even those with little knowledge of statistics – to understand. He introduced the 7 basic tools of quality. They were soon adopted by most companies and became the foundation of Japan’s astonishing industrial resurgence after World War 2.
This post will describe the 7 basic quality tools, how to use them and give you access to templates that you can use right away.
Quality Tools: What Are They?
The 7 basic tools of quality, sometimes also referred to as 7 QC tools – represent a fixed set of graphical tools used for troubleshooting issues that are related to quality.
They are called basic quality tools because they can be easily learned by anyone even without any formal training in statistics. Dr. Kaoru Ishikawa played the leading role in the development and advocacy of using the 7 quality tools in organizations for problem-solving and process improvement.
The 7 basic quality tools include;
- Check sheet
- Pareto chart
- Control chart
- Scatter diagram
- Cause-and-effect diagram
Quality tools are used to collect data, analyze data, identify root causes, and measure results in problem-solving and process improvement. The use of these tools helps people involved easily generate new ideas, solve problems, and do proper planning.
The 7 quality tools were first emphasized by Kaoru Ishikawa a professor of engineering at the University of Tokyo, who is also known as the father of “Quality Circles” for the role he played in launching Japan’s quality movement in the 1960s.
7 Basic Quality Tools Explained with Templates
The 7 quality tools can be applied across any industry. They help teams and individuals analyze and interpret the data they gather and derive maximum information from it.
Flowcharts are perhaps the most popular out of the 7 quality tools. This tool is used to visualize the sequence of steps in a process, event, workflow, system, etc. In addition to showing the process as a whole, a flowchart also highlights the relationship between steps and the process boundaries (start and end).
- To build a common understanding of a process
- To analyze processes and discover areas of issues, inefficiencies, blockers, etc.
- To standardize processes by leading everyone to follow the same steps
How to use a flowchart
- Gather a team of employees involved in carrying out the process for analyzing it
- List down the steps involved in the process from its start to end
- If you are using an online tool like Creately, you can first write down the process steps and rearrange them later on the canvas as you identify the flow.
- Identify the sequence of steps; when representing the flow with your flowchart, show it from left to write or from top to bottom
- Connect the shapes with arrows to indicate the flow.
To learn more about flowcharts, refer to our Ultimate Flowchart Tutorial.
A histogram is a type of bar chart that visualizes the distribution of numerical data. It groups numbers into ranges and the height of the bar indicates how many fall into each range.
It’s a powerful quality planning and control tool that helps you understand preventive and corrective actions.
- To easily interpret a large amount of data and identify patterns
- To make predictions of process performance
- To identify the different causes of a quality problem
How to make a histogram
- Collect data for analysis. Record occurrences of specific ranges using a tally chart
- Analyze the data at hand and split the data into intervals or bins
- Count how many values fall into each bin
- On the graph, indicate the frequency of occurrences for each bin with the area (height) of the bar.
Here’s a useful article to learn more about using a histogram for quality improvement in more detail.
Cause and Effect Diagram
This tool is devised by Kaoru Ishikawa himself and is also known as the fishbone diagram (for it’s shaped like the skeleton of a fish) and Ishikawa diagram.
They are used for identifying the various factors (causes) leading to an issue (effect). It ultimately helps discover the root cause of the problem allowing you to find the correct solution effectively.
- Problem-solving; finding root causes of a problem
- Uncovering the relationships between different causes leading to a problem
- During group brainstorming sessions to gather different perspectives on the matter
How to use the cause and effect diagram
- Identify the problem area that needs to be analyzed and write it down at the head of the diagram
- Identify the main causes of the problem. These are the labels for the main branches of the fishbone diagram. These main categories can include methods, material, machinery, people, policies, procedures, etc.
- Identify plausible sub-causes of the main causes and attach them as sub-branches to the main branches.
- Referring to the diagram you have created, do a deeper investigation of the major and minor causes
- Once you have identified the root cause, create an action plan outlining your strategy to overcome the problem
The scatter diagram (scatter charts, scatter plots, scattergrams, scatter graphs) is a chart that helps you identify how two variables are related.
The scatter diagram shows the values of the two variables plotted along the two axes of the graph. The pattern of the resulting points will reveal the correlation.
- To validate the relationship between causes and effects
- To understand the causes of poor performance
- To understand the influence of the independent variable over the dependent variable
How to make a scatter diagram
- Start with collecting data needed for validation. Understand the cause and effect relationship between the two variables.
- Identify dependent and independent variables. The dependent variable plotted along the vertical axis is called the measures parameter. The independent variable plotted along the horizontal axis is called the control parameter.
- Draw the graph based on the collected data. Add horizontal axis and vertical axis name and draw the trend line.
- Based on the trend line, analyze the diagram to understand the correlation which can be categorized as Strong, Moderate and No Relation.
Check sheets provide a systematic way to collect, record and present quantitative and qualitative data about quality problems. A check sheet used to collect quantitative data is known as a tally sheet.
It is one of the most popular QC tools and it makes data gathering much simpler.
- To check the shape of the probability distribution of a process
- To quantify defects by type, by location or by cause
- To keep track of the completion of steps in a multistep procedure (as a checklist)
How to make a checksheet
- Identify the needed information.
- Why do you need to collect the data?
- What type of information should you collect?
- Where should you collect the data from?
- Who should collect the data?
- When should you collect the data?
- How should you measure the data?
- How much data is essential?
2. Construct your sheet based on the title, source information and content information (refer to the example below)
3. Test the sheets. Make sure that all the rows and columns in it are required and relevant and that the sheet is easy to refer to and use. Test it with other collectors and make adjustments based on feedback.
The control chart is a type of run chart used to observe and study process variation resulting from a common or special cause over a period of time.
The chart helps measure the variations and visualize it to show whether the change is within an acceptable limit or not. It helps track metrics such as defects, cost per unit, production time, inventory on hand, etc.
Control charts are generally used in manufacturing, process improvement methodologies like Six Sigma and stock trading algorithms.
- To determine whether a process is stable
- To monitor processes and learn how to improve poor performance
- To recognize abnormal changes in a process
How to create a control chart
- Collect the data and divide it into subgroups based on
Here’s how to create a control chart from step 1.
The Pareto chart is a combination of a bar graph and a line graph. It helps identify the facts needed to set priorities.
The Pareto chart organizes and presents information in such a way that makes it easier to understand the relative importance of various problems or causes of problems. It comes in the shape of a vertical bar chart and displays the defects in order (from the highest to the lowest) while the line graph shows the cumulative percentage of the defect.
- To identify the relative importance of the causes of a problem
- To help teams identify the causes that will have the highest impact when solved
- To easily calculate the impact of a defect on the production
How to create a Pareto chart
- Select the problem for investigation. Also, select a method and time for collecting information. If necessary create a check sheet for recording information.
- Once you have collected the data, go through them and sort them out to calculate the cumulative percentage.
- Draw the graph, bars, cumulative percentage line and add labels (refer to the example below).
- Analyze the chart to identify the vital few problems from the trivial many by using the 80/20 rule. Plan further actions to eliminate the identified defects by finding their root causes.
What’s Your Favorite Out of the 7 Basic Quality Tools?
You can use these 7 basic quality tools individually or together to effectively investigate processes and identify areas for improvement. According to Ishikawa, it’s important that all employees learn how to use these tools to ensure the achievement of excellent performance throughout the organization.
Got anything to add to our guide? Let us know in the comments section below.