In almost any area of life, a person from time to time is faced with the fact that certain obstacles and problems arise on his way. But it is not always possible to determine the true cause of the appearance of a particular problem, and it itself can only be a visible consequence of something that is hidden from our attention somewhere inside ourselves or the activity in which we are engaged. And in order to understand the main causes of problems and eliminate them, it is very convenient to resort to the use of a technique developed specifically for this purpose - the diagram of Kaoru Ishikawa, a professor at the University of Tokyo and a leading specialist in quality management. This diagram is also known as Root Cause Analysis Diagram, Cause and Effect Diagram, and Fishbone Diagram. The presented lesson is dedicated to describing this method as a useful tool in any work and everyday life.
From the history
K. Ishikawa was a Japanese researcher in the field of quality. In the mid-twentieth century, he became involved in quality management methods and their active implementation in Japanese enterprises.
He proposed a new graphical method for quality management called the cause-and-effect diagram or Ishikawa diagram, which is also called the “fishbone” or “fishbone”.
This method, one of the simple quality assurance tools, is known to everyone in Japan - from schoolchildren to the president of a company.
Ishikawa originally introduced the “six M” rule for his diagram (all words in English that determine production causes leading to different results begin with the letter “M”): people (man), material (material), equipment (machine) , method, management, measurement.
Today, the Ishikawa cause-and-effect diagram is used not only for quality analysis, but also in other areas, and therefore the first-order causes may no longer be the same.
The Five M's Rule
Despite the apparent simplicity of construction, Ishikawa’s “fish bone” requires a thorough knowledge of the object of analysis from the performers, a clear understanding of the mutual dependence and influence of factors on each other.
To facilitate the construction of such a scheme, you can use the rule of five “M”, which was proposed by its author. It lies in the fact that when analyzing many real situations, the primary (root) causes are the following:
- Man (people) - reasons that are associated with the human factor.
- Machines (machines or equipment).
- Materials - reasons related to resources or materials.
- Methods (methods, technologies) - reasons associated with the organization of processes.
- Measurements (measurements or finances).
This is why the Ishikawa diagram is sometimes called the “5M analysis diagram.”
Classification of causes that form the “skeleton” of the diagram
The Ishikawa diagram consists of a central vertical arrow, which actually represents the effect, and large “edges” approaching it, which are called first-order causes. Smaller arrows, called second-order causes, approach these “edges,” and even smaller arrows approach them, called third-order causes. Such “branching” can take a very long time, up to reasons of the nth order.
Using the brainstorming method to create a diagram
In order to build an Ishikawa diagram, you must first discuss with your team the existing problem and what the most important factors influence it.
The method of brainstorming or brainstorming assumes that not only employees of a certain enterprise participate in the discussion, but other persons can also take part, since they have an “open eye” and approach solving the problem from an unexpected angle.
If during the first stage of discussion it is not possible to reach a consensus on the causes causing a certain effect, then as many stages as necessary are carried out to identify the main factors.
During the discussion, no ideas are discarded; all of them are carefully recorded and processed.
How to build an Ishikawa diagram in Excel
It is quite difficult to construct an Ishikawa diagram using Excel. But you can analyze the weight of each factor. And based on the schedule, find the optimal way to solve the problem.
Let's look at our example. The found factors do not have a numerical expression. For illustration, let's evaluate them in points.
Let's sort the numbers in ascending order. Let's calculate the share of each factor with a cumulative total.
Let's illustrate the scores in the form of a histogram. And the share is in the form of a graph with markers.
The diagram shows that in order to solve the problem that has arisen, you need to work mainly with the first three factors.
Construction order
Constructing an Ishikawa diagram involves several steps. The first is the correct formulation of the problem:
- It is written in the vertical center of the sheet and right-aligned horizontally. As a rule, the inscription is enclosed in a rectangle.
- First-order causes lead to the problem-consequence, which are also mostly placed in rectangles.
- The reasons of the first order are led by arrows to the reasons of the second order, to which, in turn, the reasons of the third order are brought and so on up to the order that was determined during the brainstorming.
As a rule, the diagram should have a title, date of compilation, and object of study. In order to determine which reasons belong to the first order, and which to the second, etc., it is necessary to rank them, which can be carried out during a brainstorming session or using a mathematical apparatus.
The main principles of working with the circuit
When compiling and analyzing an Ishikawa diagram, it is important to adhere to the following rules:
- It is necessary to take into account everything, even the most insignificant factors and problems. Only in this way does it become possible to find the root cause of the situation, and therefore to find the most effective solution to it.
- During the analysis, it is important to evaluate factors according to their significance. Thus, the root factors are identified - those that influence the situation the most.
- By entering the most complete information into the diagram (names of reasons, dates, names of participants, names of products), the situation or problem becomes clear and visual.
- Important! The process of search and analysis, interpretation of problems and factors is a fundamental part in creating a holistic picture and those specific actions or directions of movement that can solve a problem or resolve a situation.
Analysis of the causes of product defects
Let's look at the Ishikawa diagram using the example of analyzing the causes of product defects.
In this case, the consequence (problem) is a manufacturing defect.
During brainstorming, various reasons affecting product defects were identified. As a result of reaching a consensus by the participants in the brainstorming session, all the reasons were ranked, the unimportant ones were discarded and the most important factors were retained.
The first-order reasons included materials, equipment, components, labor, working conditions and technology.
They are directly influenced by second-order reasons: impurities, humidity, delivery, accuracy, control, storage, air environment, workplace, production culture, machine age, maintenance, discipline, qualifications, experience, tools, measuring instruments, technological discipline, documentation , equipment (its availability).
Second-order reasons are influenced by third-order reasons, which include temperature, storage humidity, inspection acceptance, lighting and noise at the workplace, and quality of equipment.
All these reasons are placed in appropriate places and an Ishikawa diagram is constructed. An example is shown in the figure. At the same time, you need to understand that other reasons may be identified by another group.
Compilation method
The main goal is to have three to six main factors that cover all possible influences. Based on the results of constructing the Ishikawa/Ishikawa diagram, the depth of such a tree reaches four or five levels. The depth of the levels allows you to visually assess the picture of all possible root causes of a particular problem. If there is difficulty with the main branches, then standard headers can be used:
Staff (people)
include factors determined by the condition and capabilities of a person. For example, this is a person’s qualifications, his physical condition, experience, etc.
Working Method (Technology)
includes the manner in which work is performed, as well as everything related to the productivity and accuracy of the performed operations of the process or activity.
Mechanisms
– these are all factors that are determined by the equipment, machines, devices used in performing actions. For example, the condition of the tool, the condition of the devices, etc.
Materials
- these are all the factors that determine the properties of the material in the process of performing work. For example, the thermal conductivity of the material, viscosity or hardness of the material.
Control
– these are all factors influencing the reliable recognition of errors in the execution of actions.
External environment (environment)–
These are all factors that determine the influence of the external environment on the performance of actions. For example, temperature, light, humidity, etc.
The main question when constructing a diagram
When analyzing any Ishikawa diagram, it should be accompanied by the question “Why?” First we ask this question in relation to the problem: “Why did this problem arise?” By answering this question, first-order reasons can be identified. Next, we ask the question “Why?” in relation to each of the reasons of the first order and, thus, we identify the reasons of the second order, etc. They are also usually not isolated, but in relation to the reasons of the third order and further, it is more correct to ask the question not “Why?”, but “What? » or “What exactly?”
Once you learn to answer these questions using the examples of an Ishikawa diagram, you will learn how to build one yourself.
Graphic rules
When drawing a fishbone diagram, large first-order arrows are attached to the main horizontal arrow, which depicts our object of analysis, which indicate root factors or groups of factors that influence the object. Arrows of the first order are followed by arrows of the second, and arrows of the third, and so on, until all the factors influencing the object or situation are taken into account.
Moreover, each subsequent arrow in relation to the arrow of the previous order is a cause, and each subsequent one is a consequence.
The size of the picture and its shape are absolutely not important. The main thing is to correctly distribute the subordination and mutual dependence of factors.
Moreover, the clearer the fishbone is, the better the diagram looks and reads.
Consideration of the problem “Scatter in details”
Let's look at Ishikawa diagrams using an example of an enterprise.
An industrial enterprise engaged in the production of any parts is often faced with the problem of variation in part sizes.
To solve this problem, it is necessary to gather technologists, workers, suppliers, managers, engineers, and you can invite other people who will help find approaches that are not provided for by specialists in their field.
With a well-conducted analysis, it is not enough to identify only the factors causing the problem; they must be correctly ranked. This can be done during brainstorming, after the process of identifying causes has been completed. Each group member must evaluate the significance of individual reasons from his own point of view, after which the overall significance of the reasons will be determined.
In the presented Ishikawa diagram, using the example of an enterprise, the following first-order reasons were identified: workers, materials, technology, machine, measurements, environment and management.
The figure shows second and third order causes. Asking "Why?" So what?" you can get to the root cause that created the problem.
The group members determined that the most significant indicators affecting the scatter of parts are the measurement period and the accuracy of the instruments.
Thus, the significance does not depend on which order the cause belongs to.
Rules
1) determine the goal;
2) all team members participate in the discussion;
3) it is recommended to exclude fruitless conversations, valuing ideas and conscious handling of facts;
4) there must be teamwork in the development of any thoughts expressed to team members;
5) participants should not feel afraid to express their ideas;
6) criticism is not allowed, all ideas are written down, not a single idea is immediately rejected;
7) proposals are not limited only to factors related to the speaker’s activities;
team members should be encouraged to unleash their creative potential;
9) management personnel are not recommended to speak out first;
Example of a finished diagram
Let's try to understand the principle of constructing an Ishikawa diagram using an example. The key problem, and therefore the title of the diagram, will be as follows: “Defects of finished products at the enterprise.”
- First, we define the main problem, which will become the name of the “ridge” of the scheme. So, the basis of the diagram is called “Defects of finished products”.
- We determine the primary factors that are the cause of this problem; they will serve as the names of the blocks for the “bones” of our scheme. The main reasons for the appearance of defects in an enterprise include: equipment, personnel, environment, work technology and materials.
- Now let's move from the general to the specific. Smaller causes of problems should be included in each block. Under the “bone” with the name “Equipment” we write all the problems associated with it, for example, outdated machines, breakdowns, etc. In the “Personnel” section we write: unskilled workers, stressful situations, insufficient motivation, etc. The block under The title “Technology” may include the following problematic facts: incorrect order of work, insufficient fastening force, etc. We work according to this principle with each section.
- After the entire diagram is constructed, every factor, even the smallest one, will be before your eyes, based on it, a “brainstorming” begins, the logical conclusion of which is the solution to the dominant problem.
Place problematic factors according to their degree of significance, i.e. the main ones closer to the ridge, gradually moving away. This way, it will be clearly visible which problem is worth thinking about first, and which points can be put into the background.
Features of the method
The Ishikawa diagram, like any phenomenon in human life, has its positive and negative qualities. Before you start working, you need to get to know them.
Positive points
- Diagramming promotes creative thinking.
- A non-standard approach to solving a problem is much more interesting and productive.
- The Ishikawa type of diagram allows you to arrange various phenomena according to their degree of importance, which provides a clear opportunity to notice in which direction you should move.
- This method allows you to trace the internal relationship of each problem and its causes.
- The main positive aspect is visibility, which always simplifies the process of establishing relationships and speeds up the search for solutions.
- In order to carry out this technique with subordinate personnel, it is not at all necessary to look for highly qualified employees; even the most mediocre employee can cope with this task.
Negative points
- Often the scheme turns out to be very difficult, which significantly slows down the search for solutions to problems.
- Unfortunately, it is not possible to check the diagram in the opposite direction, i.e. the logic behind the appearance of problematic facts is not visible.
- This method, like any other, allows for errors in drawing up the diagram. No one is immune from the inclusion of incorrect conclusions and factors in the structure. In this case, there can be only one solution: be more attentive to the discussion, look at each proposal from a critical point of view.
As you can see, there are much more positive aspects than negative ones, which is why the Ishikawa diagram technique is quite popular these days.
The Ishikawa diagram can be used not only to solve production problems; recently, psychologists have increasingly begun to use this technique.
Unique ways of solving problems help a person to dig deeper into himself and get to the roots of the problems. This method is excellent for solving family problems; in this case, the spouses will together look for the causes of troubles and ways to solve them.
This kind of work in itself brings people together, in addition to helping to eradicate the problem at the root.
Advantages and disadvantages of the method: continued research
The main advantages of the method used:
- unleashing creative potential;
- finding interdependencies between causes and effects, determining the significance of causes.
The main disadvantages when using this tool:
- there is no possibility to check the diagram in reverse order;
- the diagram can be significantly complicated, which will complicate its perception and the ability to draw logical conclusions.
In this regard, the analysis of causes and consequences must be continued using other techniques, primarily such as A. Maslow’s pyramid, Pareto diagram, stratification method, control charts and others. For a simple solution, an analysis using a cause-and-effect diagram may be sufficient.
Advantages
- involvement of competent experts in the work of the group;
- application of structured analysis;
- consideration of all probable assumptions and hypotheses;
- graphical display of results in an easy-to-read form;
- identifying areas where additional data is needed;
- the ability to identify factors that may cause the event in question for both favorable and undesirable outcomes. A positive outlook on a problem can encourage greater responsibility and involvement among participants;
- the results can be used as input to FMEA or FTA.
