Cause and Effect Diagram in Quality Control

The cause-and-effect diagram is one of Total Quality Management tools. It is also called an Ishikawa diagram because Kaoru Ishikawa developed it or fishbone diagram because the complete diagram resembles a fish skeleton. The diagram illustrates the main causes and subcases leading to an effect. It is used to organize and graphically display multiple causes with a particular effect.

It is tool for team brainstorming used to identify potential root causes to problems. Because of its function it may be referred to as a cause and-effect diagram. In a typical Fishbone diagram, the effect is usually a problem needs to be resolved, and is placed at the "fish head". The causes of the effect are then laid out along the "bones", and categorized into different types along the branches. Further causes can be laid out alongside further side branches.  

This tool can be applied at different stages of construction projects to analyze causes of rejection and take requisite preventive or remedial action; develop a system for the preparation and processing of design drawings and documents, execution/installation of work, processing of shop drawings; and many other applications.

Cause and Effect Diagram Objectives

The leading goal of the cause and effect diagram is to illustrate in a diagrammatic way the relationship between a given consequence and all factors that effect this consequence. The main objectives of this tool are:

•                Determining the root causes of a problem.
•        Focusing on a specific issue without resorting to irrelevant discussion.
•        Identifying areas where there is a lack of data.

The Importance of Cause and Effect Diagram

•             Encourages creativity through a brainstorming process.
•      Useful in brainstorming sessions to focus conversation.
•      Provides a visual image of the problem and potential categories of causes.
•     Allows various categories of causes to be explored and uncovers bottlenecks in your processes.

What is Cause and Effect Diagram?

Dr. KaoruIshikawa, a Japanese quality control statistician, invented the fishbone diagram. It is often also referred to as the Ishikawa diagram. The fishbone diagram is an analysis tool that provides a systematic way of looking at effects and the causes that create or contribute to those effects. Because of the function of the fishbone diagram, it may be referred to as a cause-and-effect diagram. The design of the diagram looks much like the skeleton of a fish. Therefore, it is often referred to as the fishbone diagram. A cause-and-effect diagram can help identify the reasons why a process goes out of control. Often the fishbone diagram can be used to summarize the results of a brainstorming session, identifying the causes of a specified undesirable outcome. It helps to identify root causes and ensures a common understanding of the causes.

There are six steps that are used to perform a cause-and-effect analysis:

Step 1. Identify the problem to analyze its technical cause.

Step 2. Select an interdisciplinary brainstorm team.

Step 3. Draw a problem box and prime arrows.

Step 4. Specify major categories contributing to the problem.

Step 5. Identify a defect cause.

Step 6. Identify corrective action and perform the analysis in the same manner as for the cause and effect analysis.

The cause and effect diagram can be used:

• When identifying possible causes of a problem 
• When the team’s thinking tends to fall into ruts

Procedure to Create Cause and Effect Diagram

•          Agree on a problem statement (effect). Write it at the center right of the flipchart. Draw a box around it and draw a horizontal arrow running to it.
•          Brainstorm the major categories of causes of the problem. If there is difficulty here, use generic headings: method, machines (equipment), people (manpower), materials, measurement, and environment. Write the categories of causes as branches from the main arrow.
•          Brainstorm all the possible causes of the problem. Ask “Why does this happen?” As each idea is given, the facilitator writes it as a branch from the appropriate category. Causes can be written in several places if they relate to several categories or multiple relationships.
•    Ask again, “Why does this happen?” about each cause. Write sub causes branching off the causes. Continue to ask “Why” and generate deeper levels of causes. Layers of branches indicate causal relationships.
•     When the team runs out of ideas, focus attention on places on the fishbone where ideas are few.

Benefits of Cause and Effect Diagram

• Helps determine root causes.
• Encourages group participation.
• Uses an orderly, easy-to-read format to diagram cause and effect relationships.
• Indicates possible causes of variation.
• Increases knowledge of the process by helping everyone to learn more about the factors at work and how they relate.
• Identifies areas for collecting data.

Good and bad Cause and Effect Diagram

A good cause and effect diagram is one which explores all possibilities so it is likely to be large and complex-looking sprouts for each new related idea noted down. Be suspicious of cause and effect diagrams with few factors, or which are neat and well ordered. These may reflect a lack of knowledge of the situation, or show that the effort to draw the diagram was not creative and exhaustive enough.

The cause and effect diagram can also be drawn with right angles, which makes it less tangled, and easier to see what layer of causality is being considered at any given time.

Tips to Make a Useful Cause and Effect Diagram

•             Use an automatic diagram software instead of hand drawing to save time and effort.
•        See some examples before drawing. Understanding fishbone diagram is best achieved by studying examples.
•     Learn from others. Seek their help. Involve as many related people as possible. Collect their ideas and advice.
•      Brainstorm potential causes by asking why questions. This helps to reveal causes that are not immediately obvious.
•        Classify the causes into different categories logically so that you can present them in a more structured way.
•       Leave enough space between primary causes since you may need to add many secondary, thirdly level or even more causes.

Advantages and Disadvantages

Advantages

•          Fishbone diagrams permit a thoughtful analysis that avoids overlooking any possible root causes for a need.
•    The fishbone technique is easy to implement and creates an easy to‐understand visual representation of the causes, categories of causes, and the need.
•      By using a fishbone diagram, you are able to focus the group on the ʺbig pictureʺ as to possible causes or factors influencing the problem/need.
•        Even after the need has been addressed, the fishbone diagram shows areas of weakness that ‐ once exposed ‐ can be rectified before causing more sustained difficulties.

Disadvantages

•      The simplicity of a fishbone diagram can be both its strength and its weakness. As a weakness, the simplicity of the fishbone diagram may make it difficult to represent the truly interrelated nature of problems and causes in some very complex situations.
•          Unless you have an extremely large space on which to draw and develop the fishbone diagram, you may find that you are not able to explore the cause and effect relationships in as much detail as you would like to.

 

Quality Control in Construction Projects

Quality control (QC) is a process through which an organization intends to ensure that product quality is maintained or improved. Quality control requires the organization to create an environment in which both management and employees aim for perfection. This is done by training personnel, creating benchmarks for product quality and testing products to check for significant variations.

A main aspect of quality control is the establishing of well-defined controls to standardize both production and reactions to quality issues. Limiting scope of error by specifying which production activities are to be completed by which personnel reduces the chance that employees will be involved in tasks for which they do not have sufficient training.

Quality control (QC) is a procedure or set of procedures prepared to ensure that a manufactured product or performed service adheres to a defined set of quality criteria or meets the requirements of the client or customer. QC is similar to, but not identical with, quality assurance (QA). QA refers to the confirmation that specified requirements have been met by a product or service, whereas QC refers to the actual inspection of these elements.

Definition of Quality Control

Juran (1999), defines quality control as a universal managerial process for conducting operation so as to provide stability to prevent adverse change and to ”maintain the status quo.” To maintain stability, the quality control process evaluates actual performance, compares actual performance to goals and takes action on the difference.

Chung (1999), defines quality control as referring to the activities that are carried out on the production line to prevent or eliminate causes of unsatisfactory performance. In the manufacturing industry, including production of ready-mixed concrete and fabrication of precast units, the major functions of quality control are control of incoming materials, monitoring of the production process, and testing of the finished product.

From the foregoing, quality control can be defined as the set of measures and procedures to follow in order to ensure that the quality of a product is maintained and improved against a set of benchmarks and that any errors encountered are either eliminated or reduced. The focus of quality control is to ensure that the product and product manufacturing are not only consistent but also in line with customer requirements.

Quality Control Procedure

 The procedure for meeting the industrial goal is termed quality ‘Control,’ just as the procedure for measuring production and cost goals are termed, respectively, production ‘Control’ and cost ‘Control.’ There are normally four steps in such control:

1-    Setting Standards. Determining the required cost–quality, performance–quality, safety–quality, and reliability–quality standards for the products.

2- Appraising Conformance. Comparing the conformance of the manufactured product, or the offered service to the standards.

3-    Acting When Necessary. Correction problems and their causes throughout the full range of those marketing, design, engineering, production, and maintenance factors that influence user satisfaction.

4-    Planning of Improvements. Developing a continuing effort to improve the cost, performance, safety, and reliability standards.

Control Steps

Gryna (2001) refers to quality control as the process employed to consistently meet standards. The control process involves observing actual performances, comparing it with some standards, and then taking action if observed performance is significantly different from the standard.

Control involves a universal sequence of steps as follows:

1-    Choose the control subject, that is, choose what we intend to regulate.

2-    Establish measurement.

3-    Establish standard of performance, product goal, and process goals.

4-    Measure actual performance.

5-    Compare actual measured performance against standards.

6-    Take action on the difference.

Quality Control Techniques

There are a variety of methods, tools, and techniques that can be applied for quality control and the improvement process. These are used to create an idea, engender planning, analyze the cause, analyze the process, foster evaluation, and create a wide variety of situations for continuous quality improvement. These tools can also be used during various stages of a construction project. The following are the most commonly used quality control tools for a variety of applications to improve the quality process:

1-    Cause-and-effect diagram

2-    Check sheet

3-    Control chart

4-    Data collection

5-    Flow chart

6-    Histogram

7-    Pareto analysis

8-    Pie chart

9-    Run chart

10- Scatter diagram

Quality Control vs Quality Assurance

 According to the AmericanSociety for Quality (ASQ), quality assurance is defined as a “planned and systematic process of activities implemented in a quality system so that the quality requirements and goals for a service can be fulfilled”. The same website explains quality control as an “observation technique that comes with certain activities that are there to fulfill requirements for quality”.

So, there is a difference between these two aspects of quality management. Quality assurance ensures that the approaches, techniques, methods and processes that are designed for the projects are performed correctly, while quality control focuses on the actual quality of deliverables that are being produced under these tested methods, processes, approaches, and techniques.

The main goal of QA is to set procedures and processes in place that will minimize risk and prevent any predictable defects from happening. While the main goal of QC is to inspect the quality of everything concrete that’s done under these processes and determine if the work is meeting the quality standards of the project. QC is often used to accept or reject solutions.

Importance of Quality Control in Construction

In order to boost owner satisfaction during a construction project, the project must meet the expected quality, which can be ensured through quality assurance and quality control activities. The quality control process confirms that the project outcome meets the owner’s standards. The quality assurance process checks the quality plan and quality control process to confirm that quality standards are implemented on the project site. Understanding project requirements and standards is essential to improve the quality construction of the project. This is usually done by a team outside of the project, and the goal of this practice is to maintain quality standards, eliminate practices that are not appropriate and share best practices for quality assurance in the organization and with the project construction team. The project quality plan should be part of the project construction management plan. The quality control plan defines how quality should be handled throughout the duration of the project.

Omission the quality control procedures of a project incurs additional expenses and project delays. Having to rework increases the maintenance and opportunity costs. Structural elements that are not built according to quality assurance standards have the potential to collapse at any time, which could lead to injuries and death.

Role of Quality Control in Construction

Quality can be defined as the degree at which product is probably to meet the required specification and limits given by the construction agency. This control ensures that the work done must be of required quality and durability. This can be carried out by conducting inspection of work from the material supplier up to the finished production. Main items of control before and during construction are verifications of soil characteristics, drawings and designs, structural safety, durability, checking the quality of materials, specifications, testing of materials and inspection of equipment.

The field of quality control is multidirectional like testing of materials to be used, field and laboratory tests on mixed materials, appropriate knowledge of methods/techniques to executive staff/contractor, Precautions to be taken and various periodic tests. Firstly, materials to be used in works should be conforming to specifications required. The important step towards improving the quality of work is to ensure that all materials and fittings used in the work are conform to the standards laid down in the contract and specifications mentioned therein. As far as possible materials approved should be used in works. If standards do not exist for a particular material, the same should be purchased from some standard manufacturer and got tested from approved test labs.

Implementation of Quality Control in Construction

Quality control can be maintained by the utilization of right engineering practice, professional attitudes, good construction practices and quality. In the case of engineering structures. It may be understood as a function of making men, materials, machines and methods operate at the standards calculated to ensure that the end result of the construction conforms to the prescribed specifications as well as meets the owner/users requirement.

Quality control is a management activity used to the construction processes to set purposes. Purpose in this case being achievement of prescribed standard of performance and cost. To achieve optimum quality at minimum cost, we have to take into account all the factors that help to build quality into a product or service.

In the construction sector where main part of works are executed by the contractor the responsibility of quality control is in the contractor and he is responsible to the designer and the owner for this.

The main problems facing the development of construction projects are the technological progress of their creation, the improvement of their quality, reliability and factory finishing. These problems can be solved by developing and applying efficient and continuous quality control at each stage of production and by testing products and structures using the latest tools and machines. In the now day competitive market of construction industry if a contractor has to survive, he should be able to meet the quality requirement of the owner/user and satisfy his needs as well as meet the conformance standards. The various process involved to be able to meet the above requirement should be cost effective.

Importance of TQM Techniques in Construction Industries

Importance of TQM Techniques in Construction Industries

Because of the rapid expansion of technological development, mass production expanded, and the number of companies on the market increased. Increasing the number of alternatives on the market enables customers to compare products according to their quality along with the price. In order to survive in this competitive environment, companies must achieve customer satisfaction by ensuring optimum time, price and scope of work while maintaining quality.

Previously, quality was seen as “the quality of the final product” but in reality, it brings many benefits to companies, such as reducing waste, saving time, increasing profit and reducing occupational health and safety problems. Today, successful companies include quality at every level of their production from manufacturing to sales even in after sales technical support and adopting it as a management philosophy. This quality-based philosophy is known as Total Quality Management (TQM).

Total quality management was first adopted in the manufacturing industry, and by that time, it was adopted in other industries. In the construction industry, each project is unique, differences in the workforce, many stakeholders, and the influence of different parameters such as climatic conditions and formal regulations on projects make the implementation of TQM very difficult.

Definition of quality

‘Quality’ has been driven from the Latin word ‘quails’ that means ‘of what kind? It is used to describe goods or service specifications in any sector. The concept of quality means different things to different people. It differs from one country to another and is influenced by the standard of living, tradition, social structure, and education. Many researchers have tried to define quality in different ways:

•         ‘Fitness for purpose or use’ - Juran,
•         ‘Quality is meeting customer’s requirements’ – Oakland
•         ‘Conformance to requirements’ – Crosby,
•         ‘Quality should be aimed at the needs of the consumer, present and future’ – Deming.

In the construction industry, quality can be defined as "meeting the requirements of the owner, designer, and regulatory agencies."

The specific factors of construction industry

While the development of quality control in the construction industry is parallel to that of the manufacturing industry, many different characteristics identify the two industries. The following differences, some of them considerable, must be considered when applying a quality program to construction.

•         Almost all construction projects are unique. They are single-order, single-production products.
•                 Unlike other industries, which usually have a fixed site with similar production conditions, each construction production site always offers different conditions.
•         The life cycle of a construction project is much longer than that of most manufactured products.
•              There is no clear and uniform standard in assessing overall construction quality as is the case with manufactured materials and materials; therefore, construction projects are usually evaluated personally.
•          Since construction projects are a unilateral design project, the owner usually directly affects production.
•         Construction project participants - owner, designer, general contractor, sub-contractor, material supplier, etc. - differ for each project.

Because of these distinctive characteristics, the construction industry in general is completely different from manufacturing. This is the reason that quality control procedures that work effectively in the mass production industry have not been considered suitable for the construction industry. Thus, quality control throughout the construction industry has not evolved to the level it has reached in manufacturing.

Quality of standards

According to the ASCE manual, the primary purpose of standards is to protect the health and safety of the public. Compliance with standards should be an issue addressed early in the design phase. Without early identification of appropriate standards, rework plans and specifications can result in significant cost and delay.

Quality of drawings and specifications

Drawings and specifications are two sets of documents given to the constructor that provide technical information about the materials, the performance of the construction facility and the quality requirements. There are often discrepancies between drawings and specifications. Therefore it is important that the drawings are clear, concise and uniform. The quality of the drawings and specifications received from the designer affect the quality in the design and construction stages, and hence the quality of the construction facility.

Constructability of design

 Constructability is one of the main factors affecting design quality. According to the ASCE manual, the design specialist must consider the requirements of the constructor. The project must be constructible by those retained to build the project. Like cods, constructability and construction techniques differ in different geographical regions. In addition to the general reviews of constructability, designs should also be reviewed for efficacy and compliance with local requirements, including preliminary and post-construction operations. Preliminary design constructability and completed operational design should be reviewed in the high-quality construction programs developed by design team members. In addition, design professionals must communicate clearly and adequately with the design intention of the constructor. This is initially done with contract documents, plans and specifications. Quality design extends throughout the construction phase of the project.

ISO standards

 The ISO 9000 series includes two basic types of standards: those that address quality assurance and those that deal with quality management. Quality assurance standards are designed for contractual and evaluation purposes which are ISO 9001, ISO 9002 and ISO 9003. The Quality Management Standard is ISO 9004 and is designed to provide guidance to companies that develop and implement quality systems.

ISO standards are geared towards improving the company's production processes. A TQM system is the big picture and it means customer satisfaction and all the activities carried out by the company. A good way of viewing ISO is that the emphasis in the ISO registration is on the management of process quality. This is not intended to reduce the role of ISO in the TQM system. ISO standards provide an excellent starting point for a company that begins a TQM program.

Application of tqm in the construction industry

Achieving acceptable levels of quality has always been a real problem in the construction industry. There are significant expenses of time, money and resources each year, due to ineffective or non-existent quality management procedures. Recently, construction companies began adopting TQM as an initiative to solve quality problems. The construction industry lagged behind other industries in adopting TQM. The reason for this delay was the perception that TQM belongs only to the manufacturing industry, difficulties in measuring (what must be measured and how to measure it) the results of the continuous improvement process and the perception that implementing TQM was costly and required a long period of time.

Seven basic steps can be implemented to implement TQM in construction projects:

•         Obtaining the commitment of the owner to quality.
•         Generating awareness, educating and changing workforce attitudes.
•         Developing a process approach to total quality management.
•         Preparing project quality plans for all levels of work.
•         Establish continuous improvement.
•        Promote workforce involvement and contribution using quality control circles and motivation programs.
•         Reviewing quality plans and measuring performance.

Total Quality Management (TQM) Techniques

Concept of Total Quality Management

The need to compete in the global market stimulated total quality management (TQM) by where higher quality, lower cost, and more rapid development are substantial to market leadership. It is considered an essential requirement for any organization to compete, besides lead, in its market. TQM is a way of planning, organizing, and understanding each activity of the process and removing all the unnecessary steps routinely followed in the organization.  TQM is a philosophy that makes quality values the driving force behind leadership, design, planning, and improvement in activities.

TQM requires organizations to focus on continuous improvement. It focuses on process improvements across the long term, instead of emphasizing short-term financial gains.

 Total Quality Management Principles 

ISO document listed eight quality management principles on which the quality management system standards of the revised ISO 9000:2000 series are based. These are as follows:

Principle 1—Customer focus

Organizations depend on their customers and, therefore, should understand current and future customer needs, should meet their customer requirements, and should pursue to exceed customer expectations.

Principle 2—Leadership

Without clear and strong leadership, a business struggles. Principle 2 is concerned with the direction of the organization. The business should have clear targets, and make certain its employees are actively involved in achieving those targets.

Principle 3—Involvement of people

People at all levels are the core of an organization, and their full involvement enables their capabilities to be used for the organization’s benefit.

Principle 4—Process approach

The process approach is all concerning efficiency and effectiveness. It’s also concerning consistency and understanding that good processes also speeds up activities.

Principle 5—System approach to management

Identify, understand, and manage interrelated processes as a system participates to the organization’s effectiveness and efficiency in achieving its objectives.

 Principle 6—Continual improvement

Continual improvement of the organization’s overall performance should be a constant objective of the organization.

Principle 7—Factual approach to design making

 Effective decisions are based on the analysis of data and information.

Principle 8—Mutual beneficial supplier relationship

An organization and its suppliers are associated, and a mutually beneficial relationship enhances the ability of both to create value.

Importance of TQM

TQM places quality as a strategic goal and focuses on continuous improvement of products, processes, and cost to compete in the global market by minimizing rework, and maximizing profitability to achieve market leadership and customer satisfaction.

It is a way of managing individuals and business processes to meet customer satisfaction. TQM involves everyone in the organization in the effort to raise customer satisfaction and achieve outstanding performance of the products or services through continuous quality improvement. TQM helps in:

•         Ensure customer satisfaction
•         Increased revenues
•         Reduce waste and inventory
•         Improve design
•         Adapt to changing markets and regulatory environments
•         Increase productivity
•         Eliminate defects and waste
•         Increase job security
•         Improve employee morale
•         Reduce costs
•         Increase profitability

TQM Models

Credits for the process of TQM go to many philosophers and their teachings. Drucker, Juran, Deming, Ishikawa, Crosby, Feigenbaum and many others who have studied organizational management have contributed effectively to the process of TQM.

There are many models of total quality management

•         Deming Application Prize
•         Malcolm Baldrige Criteria for Performance Excellence
•         European Foundation for Quality Management, and
•         ISO quality management standards

It is really not necessary that each organization should adopt and implement the same model.

Some popular TQM processes

Three types of TQM that are relevant and widely used include:

 ISO 9000

Created in the 1987, by International Organization for Standardization- compasses an entire family of quality management systems standards.  ISO 9000 focuses on people and leadership while also ensuring that products meet a minimum standard of quality.

Lean manufacturing

Developed in Japan by automobile manufacturer Toyota, it is a process focused on minimizing waste while increasing value.

Six Sigma

Developed in the 1980s at Motorola, is a set of techniques for improving processes in an organization. This method aims to improve product quality by identifying and eliminating variability that can cause defects.

Implementing TQM

W.Edwards Deming, the godfather of quality, had 14 points for implementing TQM in a company. Consider this variation of those points:

•         Create constancy of purpose to improve product and service.
•    Adopt a new philosophy for the new economic age with management learning what their responsibilities are and by assuming leadership for change.
•        Cease dependence on mass inspection to achieve quality by building quality into the product.
•     End awarding business on price. Award business on total cost and move toward single suppliers.
•        Aim for continuous improvement of the system of production and service to improve productivity and quality and to decrease costs.
•         Institute training on the job.
•        Institute leadership with the aim of supervising people to help them to do a better job.
•    Drive out fear so that everyone can work effectively together for the Organization.
•      Break down barriers between departments. Encourage research, design, sales and production to work together to foresee difficulties in production and use.
•      Eliminate slogans, exhortations and numerical targets for the workforce since they are divisory and difficulties belong to the whole system.
•     Eliminate quotas or work standards and management by objectives or numerical goals; leadership should be substituted instead.
•         Remove barriers that rob people of their right to pride in their work.
•         Institute a vigorous education and self-improvement program.
•         Put everyone in the company to work to accomplish the transformation.