Methods of management and quality controlaterelak.zut.edu.pl/fileadmin/Studenci/lecture_1-5.pdf ·...

Zachodniopomorski Uniwersytet Technologiczny w Szczecinie Wydział Inżynierii Mechanicznej i Mechatroniki

Methods of management and quality control

Lecture 1-5 – introduction, quality tools (10h)

Dr. eng. Agnieszka Terelak-Tymczyna

Course Literature

1. Ed. By Nikkan Kogyo Shimbun: Poka-Yoke: improving quality by preventing defects, 1998

2. Shigeo Shingo: Zero quality control: source inspection and poka-yoke system, 1986,

3. Shigeo Shingo: A revolution in manufacturing: the SMED system.

4. Montgomery, Douglas of quality management and control C.: Statistical quality control: a modern introduction, 2009

5. Allen, Theodore T.: Introduction to engineering statistics and six sigma: statistical quality control and design of experiments and systems, 2006.

6. Besterfield, Dale H.: Quality control, 2004

Definition of quality

Quality- all characteristics and properties of the product or service

affecting the ability of the product to satisfy stated or projected needs.

Quality inspection- activities such as measuring, testing, use of

tests for one or more characteristics of a product or service and comparing the result with the established requirements to determine compliance.

Quality control- position of the same emphasis on control, but the

additional inclusion in the system, production workers and creating feedback loops between the results of inspection and production line. Based on the results of the audit the manufacturing process is modified in order to obtain products which conform to the specifications

Definition of quality

Quality is determined by a series of requirements and features, including:

• Compliance with standards • Durability • Reliability • Aesthetics • Ease of maintenance and repair

Definition fo quality control

Quality control is a system to prevent defects and shortcomings, the method and operation of the system in place to ensure customer quality requirements by making appropriate product features and characteristics in order to achieve economically efficient quality control involves monitoring the process and eliminating causes of unsatisfactory contractor.

Place in the management of quality control

Quality Management-coordinated activities managing the organization and its supervision according to the quality

Quality Planning - the part of quality management focused on setting quality objectives and associated resources necessary for the achievement of quality objectives

Quality assurance - part of quality management focused on providing confidence that quality requirements will be met

Quality Control - part of quality management focused on fulfilling the requirements for the quality

Quality Improvement - Part of quality management focused on increasing capacity to meet quality requirements

Development of the concept of quality management

Quality Inspection - sort - scrapping - repair - correction

1920 1940 1960 1980 2000 2020

Respond to customer needs

Deliver the product complies with the specification

Quality control - quality planning - selfcontrolling - statistical control - product testing

Quality assurance - statistical process control - management responsibility - quality system - system audits - supporting methods - quality costs analysis

TQM - universal participation - continuous improvement - process approach - system approach - partnership relations with suppliers

Mas

s p

rod

uct

ion

– Fo

rd

Fun

dam

enta

ls o

f sc

ien

tifi

c m

anag

emen

t -

Tayl

or

Co

ntr

ol c

har

ts-

Shew

har

t

Qu

alit

y co

ntr

ol-

Is

hik

awa

14

ru

les

- D

emin

g

Kai

zen

- T

oyo

ta

Six

Sigm

a -

Mo

toro

la

Stan

dar

s IS

O 9

00

0

Stan

dar

ds

ISO

9

00

0:2

00

0

Stan

dar

s IS

O

90

00

:20

08

Basic techniques of problems diagnosis and analysis

Error Detection

Check Sheets

Histogram

Control Charts

Error analysis Pareto Diagram Ishikawa Diagram Cause and Effect

Diagram

Scatter Diagram Process Flow

Diagram

Seven tradittional quality tools


Problem analysis

Affinity Diagram Relation Diagram

Deciding about action

Matrix Data Analysis Chart

Tree Diagram

Process Decision Program Chart(PDPC)

Activity Network Diagram

Seven management quality tools

Matrix Diagram

The sequence of activities - resource planning


Process Flow Diagram

Block diagram applies to: • description of the existing process, • designing a new process. It is a schematic diagram that shows the flow of the product or service as it moves through the various processing stations or operations. The diagram makes it easy to visualize the entire system, identify potential trouble spots, and locate control activities.



Name Graphic symbol Description/Function

Start/Stop

Indicates the beginning and end of the process

Execution Shall contain the individual actions that must be done to make the process has been carried out

Condition Shall contain the condition that determines the way further down the road proceeding. From the symbol facing the two calls: Yes (if the condition is met) and NO (if the condition is not met)

Process Using this symbol you can show a reference to another process

Arrow It is used to connect the symbols and show the direction of the process


Process Flow Diagram START

Enter the length of the three sections of the triangle satisfy the condition

Select the longest stretch

Calculate the square of the length of the longest stretch

Calculate the squares of the lengths of two shorter sides

Calculate the sum of the squares of the lengths of two shorter sides

Is the sum of the squares of the shorter sides is

equal to the square on the longest side

The triangle is not rectangular

The triangle is rectangular

STOP



Flow diagram for order entry.


Cause-and-Effect Diagram

A cause-and-effect (C&E) diagram is a picture composed of lines and symbols designed to represent a meaningful relationship between an effect and its causes. It was developed by Dr. Kaoru Ishikawa in 1943 and is sometimes referred to as an Ishikawa diagram. C&E diagrams are used to investigate either a "bad" effect and to take action to correct the causes or a "good" effect and to learn those causes responsible. For every effect, there are likely to be numerous causes.



Is a graphical representation of the relationship between the factors acting on the process and the effects that they cause. It is helpful in solving problems that may arise in the process. When creating a diagram, it is essential to determine how the fact that (effect) will be analyzed. This may be, for example: characteristics of quality, a problem that needs to be solved, a result that needs to be improved controls, or any other outcome, which results from some reason.



The effect is the quality characteristic that needs improvement.

Causes are usually broken down into the major causes of :

1. Man, people

2. Machine, measurement

3. Method, work methods

4. Materials

5. Management and

6. Environment.



Each major cause is further subdivided into numerous minor

causes.

For example, under work methods, we might have:

1. training,

2. knowledge,

3. ability,

4. physical characteristics,

5. and so forth.

C&E diagrams (frequently called "fish-bone diagrams"

because of their shape) are the means of picturing all these

major and minor causes.



Steps in constructing and analyzing a cause-and-effect diagram: Step 1: Identify and clearly define the outcome or EFFECT to be analyzed. Step 2: Use a chart pack positioned where everyone can see it. Draw the SPINE and create the EFFECT box. Step 3: Identify the main CAUSES contributing to the effect being studied. Step 4: For each major branch, identify other specific factors which may be the CAUSES of the EFFECT. Step 5: Identify increasingly more detailed levels of causes and continue organizing them under related causes or categories. You can do this by asking a series of WHY questions. Step 6: Analyze the diagram.



Some of the benefits of constructing a cause-and-effect diagram are that: 1. helps determine the root causes of a problem or quality; 2. characteristic using a structured approach; 3. encourages group participation and utilizes group knowledge of

the process; 4. uses an orderly, easy-to-read format to diagram cause-and-

effect relationships; 5. indicates possible causes of variation in a process; 6. increases knowledge of the process by helping everyone to learn

more about the factors at work and how they relate; and 7. identifies areas where data should be collected for further study.


Pareto Diagram

Alfredo Pareto (1848-1923) conducted extensive studies of the distribution of wealth in Europe. He found that there were a few people with a lot of money and many people with little money. This unequal distribution of wealth became an integral part of economic theory. Dr. Joseph Juran recognized this concept as a universal that could be applied to many fields. He coined the phrases vital few and useful many. Pareto Law: The empirical problem is usually about 20-30% of the causes decided by about 70-80% of the consequences.

This law can be applied to most practical problems which we face in work and everyday life, such as: 80% of absenteeism in the classroom is due to the absence of 20% of students; 20% of workers have a 80% work in organizations; 80% of defects are caused by the existence of 20% of causes; 20% of the sales staff generates 80% of sales in the company;


Pareto Diagram

A Pareto diagram is a graph that ranks data classifications in descending order from left to right. Possible data classifications are: 1. types of field failures 2. problems, 3. causes, 4. types of nonconformities, 5. and so forth.

The vital few are on the left, and the useful many are on the right. It is sometimes necessary to combine some of the useful many into one classification called other and labeled O in the figure. When the other category is used, it is always on the far right. The vertical scale is dollars, frequency, or percent.


Pareto Diagram

Sometimes a Pareto diagram has a cumulative line. This line represents

the sum of the data as they are added together from left to right. Two

scales are used:

1. The one on the left is either frequency or dollars,

2. and the one on the right is percent.


Pareto Diagram

Construction of a Pareto diagram is very simple. There are six steps: 1. Determine the method of classifying the data: by problem,

cause, type of nonconformity, and so forth. 2. Decide if dollars (best), weighted frequency, or frequency is to

be used to rank the characteristics. 3. Collect data for an appropriate time interval. 4. Summarize the data and rank order categories from largest to

smallest. 5. Compute the cumulative percentage if it is to be used. 6. Construct the diagram and find the vital few.


Pareto Diagram

Pareto diagrams are used to identify the most important problems. Actually, the most important items could be identified by listing the items in descending order. However, the graph has the advantage of providing a visual impact of those vital few characteristics that need attention. Resources are then directed to take the necessary corrective action. The cumulative percentage scale, when used, must match with the dollar or frequency scale such that 100% is at the same height as the total dollars or frequency. The use of a Pareto diagram is a never-ending process. The Pareto diagram is a powerful quality-improvement tool. It is applicable to problem identification and the measurement of progress.


Pareto Diagram

Nr Causes

The size of the decrease in sales in units

The cumulative decline in sales

The cumulative percentage decline in sales

Determination of part

1 Too high a sales price 100 100 33,33% A

2 Difficult conditions of payment 50 150 50,00% A

3 Lack of information system vendors 40 190 63,33% A

4 Low level of staff experience 25 215 71,67% A

5 Unattractive products 20 235 78,33% A

6 Low staff motivation 20 255 85,00% B

7 Bad attitude to customers 15 270 90,00% B

8 Defective Products 5 275 91,67% B

9 "Acute" competition in the market 5 280 93,33% B

10 Slow processes 5 285 95,00% B

11 Too low stocks 5 290 96,67% C

12

Improper organization of promotional campaigns 3 293 97,67% C

13 Lack of adequate sales network 3 296 98,67% C

14 Lack of proper advertising 2 298 99,33% C

15

Poorly designed processes, customer service 2 300 100,00% C


Check Sheets

The control sheet is a simple, very useful tool for helping to collect and organize all the data. Can be used on virtually every position. The main purpose of check sheets is to ensure that the data are collected carefully and accurately by operating personnel for process control and problem solving. Data should be presented in such a form that it can be quickly and easily used and analyzed. The form of the check sheet is individualized for each situation and is designed by the project team.

Checks are made on a daily and weekly basis, and some checks, such as temperature, are measured. This type of check sheet ensures that a check or test is made. Whenever possible, check sheets are also designed to show location. For example, the check sheet for bicycle paint nonconformities could have shown an outline of a bicycle with small x's indicating the location of the nonconformities.


Check Sheets

Creativity plays a major role in the design of a check sheet. It should be user friendly and, whenever possible, include information on time and location. The basic control sheets are sheets: • distribution of numerical parameter • decomposition process (similar to the histogram), • the incidence of defects • location of defects, • causes of defects.


Check Sheets

Cracks places


Check Sheets


Histogram

It describe the variation in the process. The histogram graphically shows the process capability and, if desired, the relationship to the specifications and the nominal. It also suggests the shape of the population and indicates if there are any gaps in the data.

A histogram is a type of bar chart.

Histograms are used for demonstration of numerical data in a form which can be more easily understood than a table of numbers.

The histogram can also draw the boundaries of tolerance, which can immediately give information about the involvement of defective units in total production.


Histogram


Histogram

When Are Histograms Used? 1. Summarize large data sets graphically 2. Compare measurements to

specifications 3. Communicate information to the team 4. Assist in decision making


Histogram Proceedings: 1. You should collect the necessary data (minimum n = 30 the value of the measurement) and count

the total number of measurement values. 2. Divide the range of measurement intervals (classes). 3. You can use the data contained in the following table:

4. Determine the variance values: Range= (highest value) - (lowest value)

5. Determine the number of compartments: Cell Bounderies (class width) = Range / Number of intervals

6. Make the width of the smallest number of classes, which will result in the compartments. 7. Plot the value of the scale and frequency of events. Place the bands on the horizontal axis and

frequency on the vertical axis. 8. Draw the height of each compartment. Move data from a table on the axles. All bars should have

the same width and contain a total of all the data (it should also be adjacent to each other).

Sample size n The number of intervals k

30÷50 6÷10

51÷100 7÷11

101÷200 8÷12

201÷500 9÷15


Histogram


Histogram

Normal: it shows a lot of measured values, the distribution is regarded as occurring most frequently, so if the data are arranged differently, it is often the question "why"?

Bi-or multimodal: the data come from two or more of the population treated on two different machines that are operated by different operators, produced on different shifts, etc.

With "empty" compartments: it may be due to measurement errors or inappropriate choice of the number of histogram intervals


Histogram

Negative skewness: found in the case of the characteristics which have a natural upper limit, f.e. strength of materials, it also occurs when action is taken in order to maximize the measured values, f.e. as a result of "falsification" of measurement results, sort of parts Positive skewness: found in the case of the characteristics which have a natural lower limit, eg particle size, waiting time, it also occurs when action is taken in order to maximize the measured values, eg as a result of "falsification" of measurement results, sort of parts

Uniform: the process is not monitored, with frequent adjustment process

With the "hole" is mostly the result of measurement errors


Scatter Diagram

Is a graphic illustration of the connection between the two variables. Often it is necessary to collect data to analyze the relationship between various factors. The simplest way to determine if a cause-and-effect relationship exists between two variables is to plot a scatter diagram .

. Graphs of correlation is a system of coordinates X and Y.

It is used to: 1. Determine whether there is a relationship between variables. 2. Determine the direction of the relationship. 3. Show the strength of the relationship.


Scatter Diagram


Scatter Diagram

(d) Negative Correlation May Exist (e) Correlation by Stratification (f) Curvilinear Relationship


Scatter Diagram

Correlation between two random variables X and Y is a measure of the strength (degree) linear relationship between these variables.


Control Charts

Shewhart control charts are a fundamental tool in statistical process monitoring and control, especially in mass production, to quickly determine when the process has been put out of adjustment and prevent the manufacture of products not conforming to specifications.

It presents a graphic display of process stability over time.

A control chart, illustrating quality improvement. Control charts are an outstanding technique for problem solving and the resulting quality improvement.


Control Charts

Quality improvement occurs in two situations. 1. When a control chart is first introduced, the process usually is unstable. As

assignable causes for out-of-control conditions are identified and corrective action taken, the process becomes stable, with a resulting quality improvement.

2. The second situation concerns the testing or evaluation of ideas. Control charts are excellent decision makers because the pattern of the plotted points will determine if the idea is a good one, poor one, or has no effect on the process.

Your team will benefit from using a control chart when you want to: 1. monitor process variation over time; 2. differentiate between special cause and common cause variation; 3. assess the effectiveness of changes to improve a process; 4. and communicate how a process performed during a specific period.


Control Charts


Control Charts

Control charts for the characteristics evaluated numerically (measurable):

1. Card of the mean value (X) and range (R) - is a card (X - R) 2. Card of the mean value (X) and standard deviation (s) - is a card (X - s) 3. Card individual observations (xi) and movable range (R) - is a card (xi -

R) 4. Card median (Me) and range (R) - is a card (Me-R) 5. Cumulative sum cards 6. Card moving average

Control charts for the characteristics evaluated as an alternative (unmetered)

1. Card fraction of individuals do not comply (p) 2. Card number of non-conformity (np) 3. Card number of non-compliance (c) 4. Card number of discrepancies per unit (u)


Control Charts


Control Charts Points outside the DLK and the GLK - the average sustained shift

8 points on the same side LC - permanent offset average

Increasing or decreasing trend - moving to the average

2 of 3 consecutive points in Zone A warning about a possible transfer medium

4 of 5 consecutive points in zone B-warning about a possible transfer medium

15 consecutive points in Zone C (above and below the central line) - the measurement error, reducing dispersion, control lines are set incorrectly, the elements of the samples come from different populations

14 points alternately above or below each other - more samples from different machines from different operators


Problem analysis

Affinity Diagram Relationship Diagram

Deciding about action


Tree Diagram

Process Decision Program Chart(PDPC)

Activity Network Diagram

Seven management quality tools

Matrix Diagram

The sequence of activities - resource planning


Affinity Diagram

It is a tool that gathers large amounts of language data (ideas, opinions, issues) and organizes them into groupings based on their natural Relationships. The Affinity process is often used to group ideas generated by Brainstorming


Affinity Diagram

When to Use the Affinity Diagram?

• Sift through large volumes of data • Encourage new patterns of thinking


Affinity Diagram

Creating an Affinity Diagram Step 1 - Generate ideas Step 2 - Display ideas Step 3 - Sort ideas into groups Step 4 - Create header cards Step 5 - Draw finished diagram


Affinity Diagram

What Is a Header? An idea that captures the essential link among the ideas contained in a group of cards: 1. Single card or post-it 2. Phrase or sentence 3. Clear meaning


Affinity Diagram


Relations Diagram

When to use it 1. Use it when analyzing complex situations where there are

multiple interrelated issues. 2. Use it where the current problem is perceived as being a

symptom of a more important underlying problem. 3. It is also useful in building consensus within groups. 4. It is commonly used to map cause-effect relationships, but also

can be used to map any other type of relationship. 5. Use it, rather than an Affinity Diagram, when there are logical,

rather than subjective, relationships. 6. Use it, rather than a Cause-Effect Diagram, when causes are

non-hierarchic or when there are complex issues.


Relations Diagram

Fig. 1. Using the Relationship Diagram in problem solving


Relations Diagram


Relations Diagram

The cause-effect Relations Diagram contains one or more effects and multiple causes, with arrows pointing from cause to effect. The network of arrows is built up as multiple causes interrelate. The result can be considered as a complex Cause-Effect Diagram.


Relations Diagram

Several useful points may be identified when interpreting a cause-effect Relations Diagram: 1. Arrows flowing only away from a cause indicate a root cause.

Eliminating root causes can result in subsequent causes also being eliminated, giving a significant improvement for a relatively small effort.

2. A cause with multiple arrows flowing into it indicates a bottleneck. This can be difficult to eliminate, due to the multiple contributory causes.

3. A key cause is one which is selected to be addressed by future action. Key causes may be highlighted in some way, such as double circling.


Relations Diagram


Relations Diagram How to do it

1. Form a team of between four and seven people to work on the problem.

2. Identify the type of relationship to be mapped, and how this is to be

displayed.

3. Define each problem clearly, writing it as a complete, but brief, sentence on a

3" x 5" card.

4. Produce the set of items to be related in the diagram. Write each item on a 3"

x 5" card, distinguishing item cards from problem cards, for example by

writing problem cards with heavier printing or adding a box around the text.

5. If Brainstorming was used in step 4, then put the item cards randomly in a

'parking area' where they may be transferred to the main 'organization area'.

If other methods were used, then they may already be in an order which is

worth keeping (such as Affinity groups).

6. Determine where to place the problem description card(s) from step 3 in the

organization area.


Relations Diagram How to do it

7. Select a card in the organization area and look for a card in the parking area

which answers the question identified in step 2. For a cause-effect Relations

Diagram this will be a card which is a direct cause of a problem card.

8. For each card laid in step 7, repeat the process of searching for cards in the

parking area that are directly related to it, then placing this new card nearby.

9. Review the layout with the team and use the question from step 2 to help

draw arrows between cards on the diagram as relationships are agreed.

Draw the arrows going from causes to effects. Avoid confusion where lines

cross by using a 'hump-back' bridge.

10. Identify and mark key items that are to be addressed further, such as with

shading or emboldening.

11.Treat this diagram as a first draft.

12.Review the marked changes, update the document accordingly and repeat

the review as necessary. Plan and implement concrete actions to address

key items.


Relations Diagram


Tree Diagram

The Tree Diagram is used to break down a topic into successive levels of detail. The main objective of tree diagram analysis is to identify the efficient improvement strategies to reduce and stabilize the level and distribution of dust pollution.


Tree Diagram

When to use it

1. Use it when planning, to break down a task into

manageable and assignable units.

2. Use it when investigating a problem, to discover the

detailed component parts of any complex topic.

3. Use it only when the problem can be broken down in a

hierarchical manner.

4. Use it, rather than a Relations Diagram, to break down a

problem when the problem is hierarchical in nature.


Tree Diagram

Fig. Using the Tree Diagram in Problem Solving


Tree Diagram

The Tree Diagram gives a simple method of breaking down a

problem, one layer at time, into its component parts, as Fig.


Tree Diagram

How to do it

1. Identify the objective of using the Tree Diagram.

2. Assemble a small team of people to work on the diagram.

3. Define the top-level 'root' statement. This should be a brief phrase which clearly describes the problem at this level, making it easier to identify its individual sub-components.

4. Define the process for breaking down each 'parent' statement into 'child' statements. This can be helped by defining a question to ask of the parent statement, based on the original objective defined in step 1.

5. Define the criteria to be used to identify when bottom-level 'leaves' have been arrived at, and the problem does not need to be broken down further. For example, 'Tasks that may be allocated to a single person, and will take no more than one week each to complete'.


Tree Diagram

How to do it

6. Apply the process defined in step 4 to the top-level statement from step 3, in order to produce the first-level child statements (although if the top-level statement was derived from another tool, then it may be reasonable to also derive the first-level child statements from the same place).

7. Repeat this process for each card in the first level, first checking whether the criteria defined in step 5 indicates that further breakdown is required. Arrange the child cards to the right of their parents, ensuring that family groups do not merge.


Tree Diagram

Fig. 1. Arranging the cards


Tree Diagram

How to do it 8. Continue to repeat the process until the criteria defined in step 5 are

met and no further breakdown is required. If cards become cramped together, take time to rearrange them such that all parent-child relationships between cards are clear.

9. When the diagram is complete, review the stages, looking for improvements, such as: • Statements which are in the wrong place, for example where

enthusiasm at early levels has resulted in statements that should be lower down the tree.

• Levels where the child statements together do not represent their parent very well.

• General imbalances in the tree, for example where an understood subject is pursued in detail at the expense of other subjects.

10.Use the completed tree to help achieve the objective as identified in step 1.


Tree Diagram

Fig. 1. Different shapes for Trees


Tree Diagram


Matrix Diagram

It is a tool that is used to identify the relationship between pairs of lists.

When to use it 1. Use it when comparing two lists to understand the many-to-

many relationship between them (it is not useful if there is a simple one-to-one relationship).

2. Use it to determine the strength of the relationship between either single pairs of items or a single item and another complete list.

3. Use it when the second list is generated as a result of the first list, to determine the success of that generation process. For example, customer requirements versus design specifications.


Matrix Diagram

Fig. Using the Matrix Diagram in problem solving


Matrix Diagram

Fig. Relationships between lists


Matrix Diagram

Fig. Many-to-many relationships in a matrix


Matrix Diagram

Fig. Showing and summing strength of relationship


Matrix Diagram

Fig. Different types of Matrix

Diagram


Matrix Diagram

How to do it

1. Define the objective of using the Matrix Diagram. This may be a

statement such as, 'Focus design improvements on key customer

requirements', which will be used later to direct activities.

2. Recruit a team who have the time and knowledge to work on

achieving the objective. Building a Matrix Diagram can take a lot

more effort than some of the other diagrams described in this book,

and a longer term commitment may be required.

3. Decide what needs to be compared to achieve the objective. This

will result in two or more lists being identified where the

investigation of their relationships will help to achieve the objective.

This might also include identification of criteria to help decide what

should and should not be included in the list. For example, if

comparing insects with diseases, one criterion may be to exclude

any insects which are unlikely to appear in the geographical area of

study.


Matrix Diagram

How to do it

4. Identify the appropriate matrix to use. In approximate order of

common use, these are: • The L-matrix is by far the most common diagram. If there are more than two

lists, then a set of L-matrices may still be the best approach, unless the

additional relationship mapping given by other matrices is required.

• The T-matrix is useful when there are two distinct sets of questions about a core

list, for example comparing school subjects against students and against

teachers. An indirect relationship can be inferred between the two side lists.

• The Y-matrix closes the loop on the T-matrix, and is useful for comparing three

tightly coupled lists. It can also be used as a practical simplification of the C-

matrix.

• The X-matrix is useful for comparing two pairs of complementary lists, with each

pair occupying diagonally opposite lists (as they have nothing in common and

need not be compared). For example comparing men and women against

activities in athletic and intellectual pastimes, with men and women opposite.

• The C-matrix compares three lists simultaneously, such as the people, products

and processes in a factory. Being three-dimensional, it is difficult and complex

to produce and draw. It becomes easier if there are few relationships to map.


Matrix Diagram

How to do it

5. Decide how list items are to be compared.

6. Derive the lists, using guidelines from step 3. Individual items may

be easily available, or may require significant effort to acquire, for

example when determining key customer requirements.

7. Perform the comparison of the matrices, consistently using the rules

defined in step 5.

8. Evaluate the final matrix, looking for items of significance which will

result in specific actions being carried forwards. Things to look for

include: • Unimportant items which have few or no relationships with the other

lists.

• Key items which relate to many of the items in the other lists.

• Patterns which strike you as odd, and which may bear further

investigation.


Matrix Diagram

Example Matrix Diagram



The Matrix Data Analysis Chart (MDAC) is used to identify clusters of

related items within a larger group.

When to use it

1. Use it when investigating factors which affect a

number of different items, to determine common

relationships.

2. Use it to determine whether or not logically similar

items also have similar factor effects.

3. Use it to find groups of logically different items which

have similar factor effects



Fig. Using MDAC in problem solvin



Fig. MDAC plot



Fig. Clustering



Typical items of interest on an MDAC include:

1. The behavior of logical groups of items, which might be

expected to form close clusters. For example, in a

washing powder test, logical groups might be woolen

items, acrylics and mixtures.

2. Actual clustering on the chart which might highlight

divergence from expected behavior, and prompt new

actions. For example, investigation of an unexpected

cluster of different fiber types might show that they

come from one manufacturer who has developed

processes to give different fibers with similar

specifications.


Matrix Data Analysis Chart How to do it

1. Identify the items which are to be compared, and decide on the

primary objective of using the Matrix Data Analysis Chart. For

example, a restaurant may compare menu items with the objective of

finding out what makes popular dishes.

2. Identify the measurement units for the horizontal and vertical axes of

the chart. These should be two factors which are the most critical

representations of the objective identified in step 1. For example, the

restaurant may use a survey to find the aspects of eating that their

customer most value.

3. Measure the factors identified in step 2, aiming to get realistic and

unbiased values. Thus, the restaurant might take an average of

customer ratings for texture and flavor of each menu item over several

months.

4. Draw a chart and plot each point on it. Ensure that the scale on the

axes results in the points being spread over the whole chart area.



How to do it

5. Look for significant clusters of points on the chart, and highlight them by

linking them together into a ring. The appearance and ease of

interpretation are more important than the order of linkage. Groups may

be either of:

• Items that have a close logical relationship, e.g. fish dishes.

• Items that form a close physical group on the chart.

6. Interpret the chart and act on the results. Typical activities include the

investigation into and subsequent action on:

• Why items which might be expected to group closely do not.

• Why items unexpectedly form clusters.

• Why individual items are not positioned where they were expected

to be on the chart.



Fig. MDAC example


Process Decision Program Chart

The Process Decision Program Chart (commonly just

referred to as PDPC) is used to identify potential

problems and countermeasures in a plan.

When to use it

1. Use it when making plans, to help identify potential

risks to their successful completion.

2. When risks are identified, use it to help identify and

select from a set of possible countermeasures.

3. Also use it to help plan for ways of avoiding and

eliminating identified risks.

4. It is of best value when risks are non-obvious, such as

in unfamiliar situations or in complex plans, and when

the consequences of failure are serious.



Fig. From Plan to risks and countermeasures



Fig. Risk activiti



How to do it

1. Identify the objective of using PDPC.

2. Identify the areas of the plan which need to be examined in order to

meet the objectives. If it is a large plan, then attempting to examine all

elements of it will result in a practical limitation on the effort that can be

put into each element. It is usually better to use PDPC only on the

higher risk areas of the plan.

3. Gather the people to work on the PDPC. Between them, they should

have as wide a view as possible of the situation, so that diverse risks

may be identified. These may include:

• High-level managers who can see the 'big picture' and

relationships with other people and events.

• Experts in specific elements of the plan who can see potential

problems with planned actions.

• People experienced in planning and using PDPC, who may have

discovered other problems in similar situations.



How to do it

4. Identify the criteria for making decisions during construction of the PDPC.

These include:

• How to identify a risk (step 5).

• How to select risks that need countermeasures to be identified (step 6).

• How to identify countermeasures (step 7).

• How to select countermeasures to implement (step 8).

Factors to consider when identifying selection criteria include:

• Time. How much time would a risk cost? Is it on the critical path of the

schedule? How much time could countermeasures save? Cost. What

would be the overall cost of a risk occurring? What would be the cost of a

countermeasure? Would it be worth it?

• Control. How much control do you have for preventing the risk? What

control would you have should it occur? How could you change that?

• Information. How much do you know about the risk? What warning would

you have of its impending occurrence?



How to do it

5. For each plan element to be considered, identify potential problems

that could occur. Ask, 'What if ...', using Brainstorming techniques to

identify a broad range of risks.

6. For the risks identified in step 5, decide which ones should be carried

forward onto the PDPC. These will be examined in more detail when

determining countermeasures in step 8. This may be carried out by

Voting, Prioritization Matrix or some other method for selecting items.

To keep the PDPC manageable, select only a few risks per plan

element (typically three or less).

7. Put the identified risks on the plan, using shaped boxes or some other

method to enable these risks to be clearly differentiated from then

plan elements.



How to do it

8. For each risk now on the PDPC, identify possible

countermeasures in a similar manner to the identification of

risks in step 5, but now asking, 'How can this risk be

reduced?'. Look for methods of eliminating, reducing or

handling the risk.

9. In a similar manner to step 6, prioritize these

countermeasures and select those which are to be carried

forward to the PDPC, using the criteria determined in step 4.

10. In the same way as step 7, add the selected

countermeasures to the plan under the appropriate risk item.

Steps 8 to 10 are illustrated below.



How to do it

11.Carry out or otherwise prepare the selected

countermeasures, ensuring that any changes to the plan

are fully resourced and are treated thereafter as normal

plan elements. Actions here might include:

• Changing the plan, e.g. to remove or replace high risk

elements.

• Adding new elements to the plan, e.g. verification

activities.

• Preparing contingency plans which will only be

executed should specific risks occur.


Activity Network

The Activity Network is generally used as a schedule dependent

activities within a plan. The Activity Network is sometimes called an

Arrow Diagram or PERT Chart, where PERT stands for Programmed

Evaluation Review Technique.

When to use it

1. Use it when planning any project or activity which is composed of

a set of interdependent actions.

2. Use it to calculate the earliest date the project can be completed,

and to find ways of changing this.

3. Use it to identify and address risk to completing a project on time.

4. It can also be used for describing and understanding the

activities within a standard work process.

5. The resulting diagram is useful for communicating the plan and

risks to other people.


Activity Network

Fig. Using the Activity Network in problem-solving


Activity Network

Fig. The Activity Network Diagram


Activity Network

Fig. The Critical Path and Slack


Activity Network

Fig. Risks in the Activity Network


Activity Network

How to do it

1. Define the key objective of the plan, for example, 'to lay all paving

stones in a street to a given pattern'. This forms the basic

boundary of the project and lets you identify when the job is

done.

2. Identify other constraints which may affect the actual planned

actions. These typically will be around work, time and cost. For

example, where the job must be done within a week, within a set

budget, using available manpower, to government standards, and

with minimum noise and disruption to local residents.

3. Identify the actual tasks that need to be done. This may be done

through the use of a Tree Diagram (in this case, only the bottom-

level tasks will be used in the Activity Network). Write a short

description of each task onto 3" x 5" cards. Also make space for

earliest and latest start and finish dates.


Activity Network

Fig. Writing the card


Activity Network

How to do it

4. Write on each card the time that the task will take. Other information

may also be included, such as the person (or persons) who will

perform the task, the extra tools or resources required, etc. At this

time, the person's name may not be known, but the required skill level

should be known as this might affect the time estimate. When writing

in the time, try to use the same units for each task.

5. Start from the beginning, and ask which tasks must be done first.

Place these cards to the left of the working area. If there is more than

one, place them spaced out one above the other.

6. For each task just placed, find the task cards which must immediately

follow and place these to the right. If a task should start part-way

through another task, then break the second task down into two or

more tasks to enable clear start and finish links to be made. If the

cards becomes squashed up or it is not clear from the positioning

which card follows which, take a little time to rearrange them so the

correct sequence is clear and there is space for subsequent cards to

be added.


Activity Network

Fig. Positioning the cards


Activity Network

How to do it

7. Repeat step 6 until there are no more task cards to place. If the

sequence of tasks is not clear, it can be easier to start with a

central, well-understood task, and identify tasks which must go

before and after it. Another strategy is to start at the end and

work back to the start by asking of each task, 'What task must be

done before I can do this?'.

8. Complete the links between tasks by drawing lines in the work

area between cards. To do this, the cards need to be quite firmly

attached to a work area that can be drawn on, such as a

whiteboard or large sheet of paper. When drawing the links, use

arrows to indicate which task follow which.

9. Starting with the tasks at the beginning of the diagram, complete

the early start and early finish for each task in turn, following the

arrows to the next task.


Activity Network

Fig. Calculating late start and late finis


Activity Network

How to do it

10. Starting with the tasks at the end of the diagram, complete the

late start and late finish for each task in turn, following the arrows

in the reverse direction to the previous task. A task cannot be

completed until all of its successors have been completed. The

late finish is the same as the late start of the succeeding task (for

the final tasks in the project, this is equal to the earliest

completion date, calculated in step 9). If there is more than one

successor task, then there are several possible late figures.

Select the smallest of these.

The late start for each task is simply the late finish minus the

duration of the task. The final calculation is for the earliest

completion time for the project. This is calculated in the same

way as the early start date.


Activity Network

Fig. Calculating backward


Activity Network

How to do it

11. Calculate the slack time for each task as the difference between

the early and late times. Also identify the route through the

diagram where the slack time on each task through the route is

zero. This is called the critical path, as any slippage in these

tasks will affect the overall project completion date.


Activity Network

Fig. Calculating slack time


Activity Network

How to do it

1. Evaluate and act upon the results, including checking that the final

plan meets any constraints identified in step 2. Actions may include: • Reducing the total slack in the project by rearranging tasks.

• Preventing people from having to work overtime by allocation,

reallocation and task rearrangement.

• Identifying risky parts of the plan and reducing risks by reallocation or

rearrangement.

• Recalculating the early and late times to find the effect of the above

actions on the critical path, the project completion time and the slack.

• Rebudgeting to account for the effects of rearrangement or allocation.

2. Start the tasks, using the diagram to help manage the project.

Management actions may include: • Substituting actual durations of tasks into the diagram.

• Re-estimating future task durations, using known task durations.

• Adding, modifying or removing tasks.

• Rearranging the resources used.

• Recalculating the early and late times to find the effect of the above

actions.


Activity Network

Methods of management and quality controlaterelak.zut.edu.pl/fileadmin/Studenci/lecture_1-5.pdf ·...

Documents

Transcript of Methods of management and quality controlaterelak.zut.edu.pl/fileadmin/Studenci/lecture_1-5.pdf ·...