7 quality tools

7 quality tools were created by quality practitioners over the years and collected in one group in early 50s in Japan. Along with the quality movement they were popularized as quality tools. Development of quality methods and techniques lead to creation of new set of quality tools, which extended the older one.

7 Traditional quality management tools

Traditional tools are called Magnificent seven. They are the most commonly used and they are of fundamental importance. These tools can be used on its own, but often are used as components of quality management methods. They are based on simple mathematics and statistics. Therefore, they are often called statistical process control tools. The tools include:

  1. Fish diagram – cause and effects diagram used to find many levels of causes of analysed result
  2. Check sheet – helps collecting data about quality in the process
  3. Control chart – shows variability in the process and helps to analyse it.
  4. Histogram – enables to show on chart the distribution of data. In controlled process it usually looks like Gauss curve (normal distribution)
  5. Pareto chart – shows the most important elements of the group according to chosen criteria. It uses the 80-20 rule.
  6. Scatter diagram – shows correlation between two variables
  7. Flow chart – chart presenting flow of the process.

7 new quality management tools

Along with the development of quality management 7 new tools were created. They were designed to enhance traditional tools. They enable a better information flow in the enterprise. They are very important when solving problems.

They include:

  1. Affinity diagram – finding relationships between ideas
  2. Relations diagram – diagram showing causal relations between aspects of complex situation
  3. Matrix diagram – shows relationships between many variables using many dimensions
  4. Matrix data analysis –  presents numerical data about two sets of factors in a matrix form and analyze it to get numerical output.
  5. Arrow diagram – used to show the flow of process or project, similar to CPM method
  6. Tree diagram – breaks down categories into subcategories, parts, elements, etc.
  7. Process decision programme chart – identifies what may go wrong during realization of the plan.

What are the quality tools?

If I were to list all of them in this article, you would surely be tired and not finish reading. There are numerous quality tools that can be applied to improve processes and services in order to make a good quality management .

However, over the years, some of them stood out for their high efficiency and results, and they are:

  • Flowchart
  • Control letters
  • Ishikawa diagram
  • Check sheet
  • Histogram
  • Scatter diagram
  • Pareto diagram

So the time has come to talk more about each one individually …

The 7 quality tools

1 – Flowchart

The flowchart is a diagram that expresses a particular process, or workflow, sequentially, graphically, simply, objectively and directly .

This representation is made from geometric figures that symbolize stages of the given process and are connected by arrows that indicate the direction and the sequence to be followed.

The objective is to establish a management in sight, in order to facilitate the understanding of the steps that make up a process.

Flowchart

This is a traditional example of a block flowchart, one of the simplest and most used to represent simple processes.

If you want to learn how to make a flowchart, just click the link to access the complete article about this quality tool.

2 – Control charts

A control chart is a set of time-ordered points (samples) that are interpreted as horizontal lines, called LSCs and LICs.

Control charts

The use of the Control Letter is very important for the management process, allowing the company to monitor and control its processes.

From this verification, one can act to correct any problems in the process, generating greater productivity and efficiency.

To make it easier, you can use excel to make your control chart, allowing you to update the data as your process continues to improve, so you do not have to recalculate every improvement you’ve made.

3 – Ishikawa Diagram

Ishikawa Diagram, also known as Cause and Effect Diagram or Fishbone, allows to hierarchically structure the causes of a problem or opportunity for improvement.

Ishikawa Diagram

Created by Kaoru Ishikawa, the fishbone diagram is extremely useful as it helps you explore all the potential or actual causes that result in a single defect or failure.

Given this, we can propose the best actions to solve a problem within our company.

4 – Check Sheet

A Check Sheet is the simplest quality tools tool. But, although simple, the use of the check sheet saves time, eliminating the work of drawing figures or writing repetitive numbers, without compromising the analysis of the data.

Check Sheet

These are tables, sheets or structured tables used to facilitate the collection and analysis of data. Check sheets are forms in which the collected data is filled in quickly, easily and concisely. They record data and items to be checked momentarily and also serve to identify nonconformities in the process.

5 – Histogram

The Histogram, also known as Frequency Distribution Diagram, is the graphical representation, in columns (rectangles), of a data set previously tabulated and divided into uniform classes.

  • The base of each rectangle represents a class
  • The height of each rectangle represents the amount or frequency with which the value of that class occurred in the data set.

By providing the information graphically, the Histogram allows the visualization of the central values, the dispersion around the central values ??and the form of the distribution.

Histogram

This is one of the more traditional types of histograms, called the symmetric histogram. However, anyone who thinks there is only such a histogram is wrong! As I said, there are 6 types of histograms that can be used depending on the data that needs to be represented.

6 – Dispersion Diagram

The Scatterplots, or Scatterplots, are representations of two or more variables that are organized in a graph, one in function of the other.

The diagram shows whether or not there is a correlation between two studied variables, and if there is correlation, it can be positive or negative.

By understanding the correlation between two variables and how one can influence the other, we can determine the best use of them to improve the quality and productivity of our company.

In addition, there is the possibility of inferring a causal relationship between variables, helping to determine the root cause of problems.

Dispersion Diagram

Through this diagram it is possible to study 5 types of correlations between variables, which is extremely useful when determining how a metric influences another during the execution of a process.

7 – Pareto diagram

The Pareto chart is a statistical tool that assists in decision making, allowing a company to prioritize problems when they present themselves in large numbers.

The Pareto principle classifies quality-related problems into two categories:

  • Few vital
  • Too trivial.

Pareto diagram

This principle, better known as rule 20-80, tells us that 20% of the root causes account for 80% of the problems in an organization. In other words, if we solve these 20%, we end up with a lot of the problems.

Once again we can use Excel in our favor! It is possible to do a complete Pareto diagram in Excel, and to learn how, just click on the link to access our article that explains the step by step in detail.

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