Tài liệu Project Management Professional-Chapter 6 ppt

Quality ManagementOne of the goals of project management is to meet the expectations of the stakeholders of the project.. The Guide to the PMBOK defines three areas of quality management

Quality Management

One of the goals of project management is to meet the expectations

of the stakeholders of the project Managing the quality of the proj-ect is the function that will allow this to happen Quality manage-ment will include all the work that is necessary to ensure that each of the

objectives of the project is met In the latest edition of the Guide to the Project Management Body of Knowledge, PMI emphasizes that the purpose of

the project is to meet the requirements of the stakeholders In the past, the project goal was to meet or exceed the customer’s expectations

We have discussed methods of controlling the project costs and sched-ule in the cost and time management chapters These controls cover only two of the sides of the triple constraint triangle Quality management con-trols the third side of the triangle, scope, as well as provides guidance for and assurance to meeting the other two constraints of cost and schedule It is important to recognize that in modern project management, it is important

to meet the stakeholders’ expectations

It is also important that the expectations of the stakeholders are not exceeded The customer contracts for certain deliverables, and delivering something that was not asked for can be a waste of time and money In some cases delivering more than is asked for can make matters worse

Quality should not be confused with grade Quality that is low is always going to be a problem, while a low grade is not necessarily a bad condition

A product may be developed and marketed to appeal to those who want an inexpensive product that will have a limited useful life and functionality This product may also have a lower cost Stakeholders should get what they

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pay for The quality of the item means that it is indeed what it was intended

to be

The Guide to the PMBOK defines three areas of quality management:

quality planning, quality assurance, and quality control It is important that

a distinction be made between them

The quality planning function is the process that determines which quality standards should be used to accomplish the goal of ensuring that the scope of the project fulfills the stakeholders’ expectations

The quality assurance function is a process that monitors the overall ability of the project to meet the expectations of the stakeholders The pur-pose of the quality assurance function is to provide the confidence that the project will have the proper controls to be able to meet the standards that are expected by the stakeholders The quality assurance function assures that the quality of the project will be sufficient

The quality control function is the process that is used to measure the specific items that must be monitored to determine that the project will meet the stakeholders’ expectations

The philosophy of modern quality management is that mistakes should

be prevented rather than detected It is much better to create an environment that prevents mistakes from happening rather than to spend much time and effort trying to detect problems that may have already occurred ‘‘You can’t inspect quality into a product’’ is the phrase used to state this idea

Quality Planning

The quality planning process must accomplish several things if the project is

to be successful There must be an overall quality policy, or company guide-lines, regarding projects of this type Generally, this is the common policy that will be used by all projects that the company will accomplish Each project and each interrelated project must modify the guidelines and gain approval on changes that will be required for a particular project

The result of the quality planning process is the quality plan This plan describes how the quality of the project will be assured and the functions that will be carried out by the project team to accomplish this The plan also serves to provide the additional activities that will be added to the project scope, budget, and schedule that will allow these things to happen

The quality plan should reflect the information that is gathered throughout the project All of the other areas of the management of the

project should complement the quality plan Risk is of major importance in the quality plan Areas of the project that are high in risk should have a significant influence on the quality plan

Quality Assurance

The Guide to the PMBOK defines quality assurance as ‘‘all the planned and

systematic activities implemented within the quality system to provide con-fidence that the project will satisfy the relevant quality standards.’’

Quality audits are performed to review certain important areas of the project Audits make it possible to determine what is happening in the proj-ect and whether the projproj-ect quality is meeting the standards that were deter-mined in the quality plan

The quality assurance function includes the means to continuously im-prove the quality of future projects as well Lessons learned from one project are applied to the quality plans of future projects so that there can be an ever-improving level of quality in projects completed by the organization Each member of the project team, including each of the stakeholders

of the project, is essential to the quality assurance of the project In modern thinking on quality it is the individual person performing work that is really responsible for assuring the quality of the product

Cost of Quality

As in all things in project management, there should be a favorable ratio of benefits and cost to quality (figure 6-1) This is usually referred to as preven-tion rather than cure The total cost of curing a problem once it has occurred

is generally more costly than preventing the problem in the first place It is apparent that the potential savings between the cost of defects and the cost

of prevention are great Generally, many of the costs of defects are not recog-nized in an orgarecog-nized way to reflect their true cost This is because when some of the costs of these defects are recognized, the project has been turned over to a maintenance and support function The project team may have been dissolved, and the members may be working on other projects Follow-ing is a listFollow-ing of the considerations for these costs

According to Edward Deming, ‘‘Eighty-five percent of the cost of qual-ity are the direct responsibilqual-ity of management.’’

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Figure 6-1 Economics of quality.

Optimum Point

Cost of defects Cost of inspection Total cost

Level of inspection increasing

Cost

0

20

40

60

80

100

120

140

Costs of Prevention

Additional planning

Education and training of project team and stakeholders

Inspection and testing of the internal and external deliverables of the project

Improved designs for quality purposes

Quality staff

Quality audits

Quality plan and execution

Costs of Defects

Scrap

Rework

Repair

Replacement of defective parts and inventory

Repairs after the delivery of the product

Loss of future business with the stakeholder

Legal issues for nonconformance

Liability for defect

Risk to life and property

Figure 6-2 Deming’s fourteen points.

• Constancy of purpose • Drive out fear

• Adopt a new • Break down barriers

philosophy

• Eliminate need for • Eliminate slogans,

inspection targets, and the like

• Only consider total • Eliminate management

cost, not price by standards and quotas

• Improve constantly • Remove barriers to

pride of workmanship

• Initiate OJT • Institute education

and self-improvement

• Initiate leadership • Get everyone involved

Deming’s Fourteen Points

Edward Deming is probably best known for his fourteen points on quality (figure 6-2) These guidelines were developed during Deming’s work with Japanese industries and serve as a guideline for the practice of practical qual-ity management

Quality Control

The function of quality control is to monitor specific project results to en-sure that the results match the standards that were set for the project The quality control function utilizes a number of techniques to accomplish this Many of these tools and techniques are rooted in the concepts of probability and statistics

Inspection is carried out by the observation of attributes or measure-ments An item that is supposed to be a certain size can be measured directly, and the data regarding its dimensional size can be collected All items ac-cepted will be within the acceptable allowed tolerance on the item

Items may also be inspected by attribute In this technique the item to

be inspected is made to fit or not fit into a specially designed gauge or special measuring device If the part fits into the ‘‘Go’’ gauge and does not fit into the ‘‘No Go’’ gauge, then the part is acceptable If the part does not fit into

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the ‘‘Go’’ gauge or fits into the ‘‘No Go’’ gauge, the part is considered to be bad All attribute inspections have a yes or no outcome

Attribute sampling has several advantages over measurement methods

In attribute sampling the inspection is fast and cheap, and there is little room for mistakes on the part of the inspector Measurements take a certain amount of skill and concentration As such, measurements are prone to human errors stemming from fatigue and boredom

For example, suppose a motor shaft has a design tolerance of 1.5 inches and an allowable tolerance of plus or minus 015 inches for its diameter This means that an acceptable part will have to be between 1.515 and 1.485 inches

To test this attribute, a gauge is constructed with a hole that has a diameter of exactly 1.515 inches This is a ‘‘Go’’ gauge Parts that have a diameter of less than 1.515 inches will fit into this gauge, and those that are larger than 1.515 inches will not fit

Another gauge is constructed with a hole of 1.485 inches in diameter Parts that fit into this gauge will be unacceptable, since their diameter is less than 1.485 inches This is the ‘‘No Go’’ gauge

The inspection of shafts is quick, easy, and nearly foolproof A part is taken and first applied to the ‘‘Go’’ gauge If it passes this gauge, it is imme-diately put into the ‘‘No Go’’ gauge If it fails to fit this gauge, it is an acceptable part

Sampling Inspection

Unless there are unusual requirements for extreme quality, as when death can result from a defective part, most customers will accept a certain amount

of defects The reason for this is stated in the law of diminishing returns As the desire to locate each and every defect is satisfied, it becomes more and more costly to find them One hundred percent inspections are expensive and require much time and effort In 100 percent inspections there is also the problem of the inspection itself causing damage to some of the parts This entire concept is based on the fact that the customer is willing to accept

a small number of defective parts rather than pay the high cost of trying to locate each and every defect

This policy of allowing a few unacceptable parts must be considered carefully The ultimate use of the parts must be considered In particular, it

is important that the part that is defective not create danger to life There

can be no value placed on a human life, and many court cases have awarded large settlements against companies that attempted to do so

For this reason, statistical sampling was developed Without going into the statistical details that support sampling inspection, it can be described Sampling inspection plans have been worked out and are available to quality managers to determine the parameters desired and to set up an inspection plan that will fit the type of work that they are doing

In a sampling inspection, the sample size to be taken and inspected from a given lot size is determined A sample size of fifteen parts may be taken from a lot of parts Again, according to precalculated procedures, the fifteen piece sample can contain no more than three unacceptable parts If less than three parts in the sample are unacceptable, the lot passes, and if more than three parts are unacceptable, then the lot is rejected

Acceptable Quality Level (AQL)

The rationale behind this technique is that if the acceptable quality level (AQL) was 3 percent and a sample of fifteen parts was taken from a lot of a thousand parts, there would be a very small chance that some of the bad parts would show up in the sample If more than three parts were to show

up in the sample, it could be said that the whole lot had more bad parts than the 3 percent allowed by the AQL

Because discovering all of the defective parts can be a very costly

proc-ess, most customers and suppliers agree that a certain level of defects is to be allowed in the normal process As long as this acceptable quality level (AQL)

is maintained the lot of parts is acceptable to the customer The AQL says that a lot that has fewer than 3 percent bad parts in it is acceptable

Buyer’s Risk and Seller’s Risk

When we perform sampling inspections, there is a risk that the sample will give misleading information There are four possible outcomes to this in-spection process The possibilities are:

1 The lot is good, and the sample inspection says that it is good This

is what we want

2 The lot is good, and the sample inspection says that it is not good This is not what we want

3 The lot is bad, and the sample inspection says that it is good This

is not what we want

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4 The lot is bad, and the sample inspection says that it is bad This is what we want

If the sampling inspection accepts a lot that is good or rejects a lot that

is bad, then the inspection process is working If the sampling process accepts

a lot that is really bad, this means that a lot that is really unacceptable is shipped as a good lot to the customer This is called ‘‘buyer’s risk’’ (see figure 6-3) If the sampling process rejects a lot that is really good, this means that

a lot that is really acceptable is rejected This is called ‘‘seller’s risk.’’

Other Quality Control Techniques

Flowcharts and Diagrams

Flowcharts can be helpful in understanding the cause and effect relationships between the process of performing work and the results that are inspected through measurement or attribute inspection A flow chart is simply an orga-nized way to look at the steps that have to be carried out to perform some goal There are many techniques and styles of flow charting

Cause and Effect Diagrams

The cause and effect diagram, also known as the fishbone diagram because

of its appearance, was developed by Kaoru Ishikawa This is a way of dia-gramming the flow of work that is useful in determining the cause and effect

of problems that are encountered

As can be seen in figure 6-4, the process is separated logically into branches Each of the branches can be dealt with separately If the work on one branch is excessive, a separate meeting may be used to investigate it or any other branches requiring input from more people or more time to con-sider the branch

Like the work breakdown structure, the cause and effect diagram allows for an orderly consideration of each of the possible causes of a problem and then allows for the consideration of each effect and the solution that will reduce the problem

Pareto Charts

Vilfredo Pareto is given credit for developing the concept of 80–20 rule He was an economist who found that typically 80 percent of the wealth of a region was concentrated in 20 percent of the population This concept

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Figure 6-3 Producer risk versus consumer risk.

Percent of defects

25

0 50 100

Probability

of accepting

• Accept a lot that is bad

AQL

• Reject a lot that is good

Figure 6-4 Cause and effect diagram, or fishbone diagram.

Gauge bad

Operator error

Inspection problem

Tool wear

Wrong tool

Tool problem

Rough handling

Bad material Wrong material

Wrong heat treat

Bad container

Material handling

Problems in manufacturing shafts

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