TQM - Session 9-10
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Transcript of TQM - Session 9-10
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9- 10
Quality ImprovementTools
Quali ty is free, bu t only to th ose wh o are wil l in g to pay heavi ly
for i t .
Philip Crosby
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Learning Objectives
After studying this chapter, you should be able to:
I. Explain the seven Quality control tools
Pareto Chart
Cause and Effect Diagram
Check sheet
Histogram
Scatter Diagram
Control Charts
Graph
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Seven QC Tools
The Seven Q.C. Tools were identified by the Japanese Union
of Scientists and Engineers (JUSE) as the seven most
important tools for use in Continuous Improvement.
They are primarily associated with the Study and Act steps
in the PDSA cycle. The Seven Q.C. Tools are often used in conjunction with a step-by-step
problem solving process known as the Q.C. Story.
The seven QC tools are Pareto Chart, Cause and Effect
Diagram, Stratification, Check sheet, Histogram, ScatterDiagram, Control Charts and graph
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1. Pareto Chart
A Pareto chart is a bar graph. The lengths ofthe bars represent frequency or cost (time or
money), and are arranged with longest bars
on the left and the shortest to the right. In this
way the chart visually depicts which situations
are more significant. Pareto Chart is a special
form of a bar graph and is used to display the
relative importance of problems or conditions.
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Steps in Constructing a Pareto Chart
List the activities or causes in a table and their frequency of occurrence
Place these in descending order of magnitude in the table
Calculate the total for the whole list
Calculate the percentage of the total that each cause represents
Add a cumulative percentage column to the table
Draw a Pareto chart plotting the causes on X-axis and cumulative
percentage on Y-axis. The Cumulative curve can be drawn to show the
cumulative percentage from all causes.
On the same chart, plot a bar graph with causes on X-axis and
percentage frequency on Y-axis. Analyze the diagram. Look for the break point on the cumulative percent
graph. It can be identified by a marked change in the slope of the graph.
This separates the significant few from the trivial many.
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Pareto Chart - Example
Category Number of
Complaints
Percentage Cumulative
Percentage
Cockroaches 962 43.2 43.2
Rooms temperature 505 22.7 65.9
Lighting 350 15.7 81.6
Storge space 127 5.7 87.3Stereo noise 97 4.4 91.7
Television broadcasting 83 3.7 95.4
Water 54 2.4 97.8
Towels 32 1.4 99.2
Furniture 15 0.8 100.00
TOTAL 2225
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Pareto Chart
Pareto Chart
BEQ/BOQ Complaints
Category
furn
towel
water
tv
stereo
store
light
temp
cock
NumberofComplaints
3000
2000
1000
0
Percent
100
50
0
350
505
962
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2. Cause-and-Effect Diagram
This diagram is also called as Fishbonediagram, Ishikawa diagram. The fishbone
diagram identifies many possible causes for
an effect or problem. It can be used tostructure a brainstorming session. It
immediately sorts ideas into useful categories.
The causeand-effect diagram is the
brainchild of Kaoru Ishikawa,
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Steps in Constructing a Cause and EffectDiagram
1. Write the issue (problem or process condition) on the center right side
of the Cause and Effect Diagram.
2. Identify the major cause categories and write them in the four boxes on
the Cause and Effect Diagram. You may summarize causes under
categories such as: Methods, Machine, Manpower, Materials,
Measurement, Environment
3. Brainstorm potential causes of the problem. As possible causes are
provided, decide as a group where to place them on the Cause and
Effect Diagram. It is acceptable to list a possible cause under more
than one major cause category.
4. Review each major cause category. Circle the most likely causes on
the diagram.
5. Review the causes that are circled and ask, Why is this cause?
Asking why will help get to the root cause of the problem.
6. Reach an agreement on the most probable cause(s).
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Cause-and-Effect Diagram
METHODS MACHINERY
MANPOWER
NEW OFFICEWORKINGMETHOD
MATERIALS
Office layout
Effect on other office
Remove old forms
Design new forms
Training
Teamwork
Re-designscreen
Effect Cause
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3. Check Sheet
It is also called as defect concentrationdiagram. A check sheet is a structured,
prepared form for collecting and analyzing
data. This is a generic tool that can be adapted for a
wide variety of purposes. The function of a
check sheets is to present information in anefficient, graphical format.
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Steps in Creating a Check Sheet
Clarify the measurement objectives. Ask questions such as "What is
the problem?, "Why should data be collected?, Who will use the
information being collected?, Who will collect the data?
Create a form for collecting data. Determine the specific things that will
be measured and write this down the left side of the check sheet.Determine the time or place being measured and white this across the
top of the columns.
Collect the data for the items being measured. Record each occurrence
directly on the Check Sheet as it happens.
Tally the data by totaling the number of occurrences for each category
being measured.
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Check Sheet - Sample
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Application of Check Sheet
Distinguishing between fact and opinion (example: how does the
community perceive the effectiveness of the school in preparing
students for the world of work?)
Gathering data about how often a problem is occurring (example: how
often are students missing classes?)
Gathering data about the type of problem occurring (example: What isthe most common type of word processing error created by the
students-grammar, punctuation, transposing letters, etc.?)
When data can be observed and collected repeatedly by the same
person or at the same location.
When collecting data on the frequency or patterns of events, problems,
defects, defect location, defect causes, etc.
When collecting data from a production process.
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4. Histogrm
Histograms provide a simple, graphical view of accumulated
data, including its dispersion and central tendency. In addition to
the ease with which they can be constructed, histograms provide
the easiest way to evaluate the distribution of data. A frequency
distribution shows how often each different value in a set of data
occurs. A histogram is the most commonly used graph to showfrequency distributions.
There are five types of Histograms based on five different types
of distributions and each indicates a very different type of
behavior. The various types of distributions are: Bell shaped
distribution Double-peaked distribution Plateau distribution
Comb distribution and Skewed distribution
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Histogram
Frequency Distribution
Class Lower limit Upper limit Frequency
1 35 38 1
2 38 41 2
3 41 44 4
4 44 47 5
5 47 50 8
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Histogram
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Application of Histogram
When the data are numerical.
When you want to see the shape of the datas distribution, especially
when determining whether the output of a process is distributed
approximately normally.
When analyzing whether a process can meet the customers
requirements. When analyzing what the output from a suppliers process looks like.
When seeing whether a process change has occurred from one time
period to another.
When determining whether the outputs of two or more processes are
different.
When you wish to communicate the distribution of data quickly and
easily to others.
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5. Scatter Diagram
Scatter diagrams are used to investigate the possible relationship
between two variables that both relate to the same "event." A
straight line of best fit (using the least squares method) is often
included.
The scatter diagram also shows the pattern of relationship
between two variables. Examples of relationships are : Cutting
speed and tool life, Breakdowns and equipment age, Training
and errors, Speed and gas mileage, Production speed andnumber of defective parts
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Steps in Constructing a Scatter Diagram
Collect data for variables about the causes and effects.
Draw the causes on the X-axis
Draw the effect on the Y-axis
Plot the data pairs on the diagram by placing a dot at the
intersection of the X and Y coordinates for each data pair.
Interpret the scatter diagram for direction and strength
interpreting the direction.
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Interpretation of a Scatter Diagram
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Scatter Diagram - Example
Data collected by market research teamPrices of the
Commodity/Kg in Rs22 24 26 28 30 32 34 36 38 40
Demand for the
Commodity in Kg60 58 56 50 48 46 44 42 36 32
Fig 8.1.6. Scatter diagram
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6. Control Charts
The control chart is the fundamental tool of Statistical Process Control
(SPC), as it indicates the range of variability that is built into a system
(known as common cause variation). Thus, it helps determine whether
or not a process is operating consistently or if a special cause has
occurred to change the process mean or variance.
SPC4 is used to measure the performance of a process. It is the
application of statistical techniques to determine whether the output of a
process conforms to the product or service design. All processes are
subject to certain degree of variability. Usually variations are of twotypes:
Natural variations
Assignable variations.
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Components of Control Charts
A centerline, usually the mathematical average of all the samples
plotted.
Upper and lower statistical control limits that define the
constraints of common cause variations.
Performance data plotted over time.
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Construction of Control charts
Step 1:Draw the X-axis.
Step 2:Draw the Y-axis.
Step 3: Draw the Center-line
Step 4: Draw UCL and LCL
Step 5: Analyse and Interpret
Step 6: Determine Process Capability
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Types of Control Charts
Charts for Variables
Mean chart -X bar chart
Range chart - R chart
Charts for Standard Deviation
Chartxs for attributes
p chart
np chart
c chart
u chart
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Selection of Control Charts
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Application of Control Charts
To establish a state of statistical control
To monitor a process and signal when the process goes out of control
To determine process capability
When controlling ongoing processes by finding and correcting problems as
they occur.
When predicting the expected range of outcomes from a process.
When determining whether a process is stable (in statistical control).
When analyzing patterns of process variation from special causes (non-
routine events) or common causes (built into the process).
When determining whether your quality improvement project should aim toprevent specific problems or to make fundamental changes to the process
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7. Graphs
There are many kinds of graphs employed,depending on the shape desired and the
purpose of analysis. Bar graphs compare
values via parallel bars, while line graphs areused to illustrate variations over a period of
time. Circle graphs indicate the categorical
breakdown of values, and radar charts6 assistin the analysis of previously evaluated items
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Application of QC tools in Six-Sigma
Tool DMAIC Application
Pareto chart Anayse
Cause and effect diagram Analyse
Stratification Define
Check sheet Measure, Analyse
Histogram Measure, Analyse
Scatter diagram Analyse. Improve
Control charts Control
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The Seven New QC Tools
Affinity Diagram is otherwise known as KJ Method, which was, developed
by Jiro Kawakita.
Relations diagram is derived from cause and effect diagram. It shows
cause-and-effect relationships and helps to analyze the natural links
between different aspects of a complex situation
Systematic or Tree Diagram is nothing new but an adaptation from the
diagram Functional Analysis System (FAST) Technique in value
engineering
Matrix diagramis an adaptation from the Feasibility Ranking method
Matrix of value engineering, again.
Matrix Data Analysis is from the multivariate analysis method whose
calculations are a quite complex.
Arrow diagram is nothing but derivative from PERT (Programmeevaluation and review technique) and CPM (Critical Path Methodology)
Process Decision Programme Chart (PDPC) diagram is an adaptation from
the operations research methods.
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Application of New Seven Tools
Tool Name Utilization
Affinity Diagram Used to Organize abstract thinking about a
problem.
Relations Diagram Used for determining causalities among parts of a
problem.
Systematic/Tree Diagram Planning tool.
Matrix Diagram (many types) Used to organize knowledge in a matrix format;
sometimes includes intercellular relationships.
Matrix Data Analysis Method Principal components technique is performed on
matrix data.
Arrow Diagram Used to do 'what-fifing' on flow of process.
Process Decision Program Chart
(PDPC)
Determining which processes to use by evaluating
events and prospective outcomes.
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1. Affinity Diagram
It is also called as affinity chart, K-J method. The affinity diagram
organizes a large number of ideas into their natural relationships. This
method taps a teams creativity and intuition. It was created in the 1960s
by Japanese anthropologist Jiro Kawakita. It is a tool that gathers large
amounts of language data (ideas, opinions, issues) and organizes them
into groupings based on their natural relationships.
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Construction of a Affinity Diagram
Rapidly group ideas that seem to belong together.
It isn't important to define why they belong together.
Clarify any ideas in question.
Copy an idea into in more than one affinity set if appropriate.
Look for small sets. Should they belong in a larger group?
Do large sets need to be broken down more precisely?
When most of the ideas have been sorted, you can start to enter titles for
each affinity set.
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Application of Affinity Diagram
When you are confronted with many facts or ideas in apparent chaos
When issues seem too large and complex to grasp
When group consensus is necessary
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Affinity Diagram
Human resourceissues
Lack of standard
processesand measurement
Workplace culture Resources and tools
Too much turnover No standard systemsNot enough management
support
Not enough phonelines
Untrained staffNo measurement ofwhat is and what
isnt good serviceStaff feel unappreciated
Staff arent compensated
enough
Staff morale is low
Fig 8.2.1 Affinity diagram
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2. Relations Diagram
It is also called as interrelationship diagram or digraph, network diagram.
The relations diagram shows cause-and-effect relationships. Just as
importantly, the process of creating a relations diagram helps a group
analyze the natural links between different aspects of a complex
situation.
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Steps in Constructing Relations Diagram
State clearly the issue or problem. Write it on a card and stick it to the
center of a board.
Determine the factors related to the issue. Frequently these will be the
headers from a previously completed affinity diagram. Place cards
containing these factors in a circle around the issue card.
Determine if cause-effect relationships exist between any of the cards. If
so, draw an arrow from the "cause" card to the "effect" card. Do this for
all cause/effect relationships that you can find.
Analyze the relationships. Cards that have most arrows going from them
tend to be root causes. Cards that have most arrows going to them areroot effects.
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Relations Diagram
Customer focus
Lack of focus
Indequate training time
No standard TQM method
Responsibility not clear
Lack of knowledgeof quality
improvement Lack of communicationof information
Confusion of committees
withoutorganization
Lack of TQMcommitment bytop managers
Lack of quality strategy
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Use of Relations Diagram
Identifying key or driver issues from a list of important issues.
Identifying the most important problems for solution when the number of
problems exceeds the resources available to solve all of them.
Identifying the root cause of existing problems.
Identifying key factors needed to make a decision when there is
insufficient information available to make a data-driven decision.
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3. Systematic or Tree Diagram
It is also called as systematic diagram, tree analysis, analytical tree,
hierarchy diagram. Tree Diagram is a technique for mapping out full rangeof paths and tasks that need to be done in order to achieve a primary goal
and related sub goals.
Such a diagram reveals in a simple way with clarity not only the magnitude
of the problem but also helps to arrive at methods, which are to be pursued
to achieve the results. In other words, it serves the purpose of developing
the essential means to achieve an objective or goal.
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Tree Diagram
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Use of Tree Diagram
Developing a sequence of steps that depend on each other that form the
solution to a problem.
When it is known that the implementation of some task will be a complex
sequence.
When serious consequences can occur as the result of missing a key step
in implementing the solution to a problem
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4. Matrix Diagram
The matrix diagram shows the relationship between two, three or four
groups of information. It also can give information about the relationship,such as its strength, the roles played by various individuals or
measurements.
A Matrix Diagram consists of a number of columns and rows whose
intersections are checked up, to find out the nature and strength of theproblem which help us to arrive at key ideas and analyzing the relationship
or its absence at the intersection and finding an effective way of pursuing
the problem solving method.
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Types of Matrix Diagram
An L-shaped matrix: It relates two groups of items to each other (or one
group to itself).
A T-shaped matrix: It relates three groups of items: groups B and C are
each related to A. Groups B and C are not related to each other.
A Y-shaped matrix: It relates three groups of items. Each group is related to
the other two in a circular fashion.
A C-shaped matrix: It relates three groups of items all together
simultaneously, in 3-D.
An X-shaped matrix: It relates four groups of items. Each group is related to
two others in a circular fashion.
A roof-shaped matrix: It relates one group of items to itself. It is usuallyused along with an L- or T-shaped matrix.
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Steps in Constructing a Matrix Diagram
Determine the factors that are important for making a correct selection or
assignment.
Select the type of matrix to be used. L-shaped matrices are used for two-
factor comparisons; T-shaped are used for 3-factor comparisons in that
display indirect and direct relationships; Y-shaped are used for 3-factor
comparisons showing direct relationship only.
Select the relationship symbols to be used.
Complete the proper matrix using the appropriate factors and symbols.
Examine the matrix and draw the appropriate conclusion.
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Industrial Applications of Matrix Diagram
It is often used in deploying quality requirements into counterpart
(engineering) characteristics and then into production requirements.
Establish idea conception points for the development and improvement ofsystem products
Achieve quality deployment in product materials
Establish and strengthen the quality assurance system by linking certifiedlevels of quality with various control functions
Reinforce and improve the efficiency of the quality evaluation system
Pursue the causes of non conformities in the manufacturing process
Establish strategies about the mix of products to send to market byevaluating the relationships between the products and market situations.
l
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5. Matrix Data Analysis
Matrix Data Analysis is a multivariate analysis technique called 'Principal
Component Analysis'. This technique quantifies and arranges data
presented in a Matrix Diagram, to find more general indicators that would
differentiate and give clarity to large amount of complexly intertwined
information. This will help us to visualize properly and get an insight into
the situations.
This diagram is used when the matrix chart does not provide sufficiently
detailed information. This is the only method within the New Seven that is
based on data analysis and gives numerical results.
Characteristics of Matrix Data Analysis
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Characteristics of Matrix Data AnalysisDiagram
The matrix analysis method qualifies and arranges matrix diagram data so
that the information is easy to visualize and comprehend.
The relationships between the elements shown in a matrix diagram are
quantified by obtaining numerical data for intersection cells.
Of the seven new QC tools, this is the only numerical analysis method. The
results of this technique, however, are presented in diagram form.
One major technique that this method also utilizes is known as principal-
components analysis.
U f M i D A l i Di
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Use of Matrix Data Analysis Diagram
Analyze production processes where factors are complexly intertwined
Analyze causes of nonconformities that involve a large volume of data
Grasp the desired quality level indicated by the results of a market
survey
Classify sensory characteristics systematically
Accomplish complex quality evaluations
Analyze curvilinear data
6 A Di
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6. Arrow Diagram
It is also called as activity network diagram, network diagram, activity chart,
node diagram, CPM (critical path method) chart.
The arrow diagram shows the required order of tasks in a project or
process, the best schedule for the entire project, and potential scheduling
and resource problems and their solutions.
The arrow diagram lets you calculate the critical path of the project. This
is the flow of critical steps where delays will affect the timing of the entire
project and where addition of resources can speed up the project.
St i C t ti A Di
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Steps in Constructing Arrow Diagram
Select a team that is knowledgeable about the project, its tasks, and sub
tasks.
Record all of the tasks and sub tasks necessary to the completion of the
project.
Sequence the tasks.
Assign time duration to each task.
Calculate the shortest possible implementation time schedule using the
critical path method.
Calculate the earliest starting and finishing times for each task.
Locate tasks with slack (extra) time and calculate total slack.
Update the schedule as the project is being completed.
A li ti f A Di
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Application of Arrow Diagram
Understanding and managing a complex project or task.
Understanding and managing a project that is of major importance to the
organization, and the consequences of late completion are severe.
Understanding and managing a project in which multiple activities must
take place and be managed simultaneously.
Explaining the project status to others.
Plan and follow up QC inspections and diagnostic tests
7. Precision Decision Programme Chart
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7. Precision Decision Programme Chart(PDPC)
The Process Decision Program Chart (PDPC)9 is a very useful and
powerful method to overcome a problem or a goal to be achieved which
are not familiar. With the help of PDPC we can map out all the
conceivable events or contingencies that can occur in the
implementation stage and also find out feasible counter measures to
overcome these problems.
Ch t i ti f PDPC
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Characteristics of PDPC
The PDPC diagram is a simple graphical tool, which can be used to mitigate
risk in virtually any undertaking The PDPC method helps determine, which processes to use to obtain
desired results by evaluating the progress of events and the variety of
conceivable outcomes.
Implementation plans do not always progress as anticipated. When
problems, technical or otherwise, arise, solutions are frequently not
apparent. The PDPC method, in response to these kinds of problems, anticipates
possible outcomes and prepares countermeasures that will lead to the best
possible solutions.
Establish an implementation plan for management by objectives
Establish an implementation plan for technology-development themes
Establish a policy of forecasting and responding in advance to majorevents predicted in the system
Implement countermeasures to minimize non-conformities in the
manufacturing process to set up and select adjustment measures for
negotiating process
St i C t ti A PDPC Di
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Steps in Constructing A PDPC Diagram
Select a team that is familiar with the process and possible contingencies.
Typically, this will be a group that has been close to the effort or a similar
effort.
Determine the flow of the activities of the plan and place them on a flow
chart or sequence.
Construct a tree diagram, placing prerequisite activities in a time
sequence. This can be done either a horizontal or vertical format.
At each step, ask, "What could go wrong here?" and place that
contingency on the chart.
Determine plausible explanations/solutions to each problem identified
above and place the solution on the chart.
Application of PDPC Diagram
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Application of PDPC Diagram
Exploring all of the possible contingencies that could occur in the
implementation of any new or untried plan that has risks involved.
Implementing a plan that is complex and the consequences of failure are
serious.
Implementing a plan in which there is generally a time constraint for
implementing a plan so that insufficient time is available to deal with
contingent problems as they occur.