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PROBLEM ANALYSIS TOOLS: FISHBONE DIAGRAM,
MATRIX DIAGRAM AND SCATTER
PLOT DIAGRAM
Presented to
Dr. Betty Polido in partial fulfilmentfor the Subject N414-F
Torreres, Nicel Ann M.Tohoy, Evan Cristy S.
July 3, 2012
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Objectives:
Define fishbone diagram, matrix diagram and scatterplot diagram
Enumerate situations when fishbone diagram or
cause and effect diagram should be used
Differentiate the six shaped matrix diagram
Describe the steps involved in a matrix diagram
Enumerate situation when to use a scatter plot
diagramExplain the scatter plot diagram procedure
Discuss how a fishbone diagram is constructed
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Introduction
Problem analysis tool is useful in solving
problems within an organization, group or team. It
is helpful in citing, analysing and acquiring possiblesolutions to the problem cited. It makes problem
solving and decision making easy and convenient.
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Fishbone Diagram or
Cause and Effect Diagram
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Dr. Kaoru Ishikawa, a Japanese quality control
statistician and a pioneer in quality management,
invented the fishbone diagram. The technique was thenpublished in his 1990 book, "Introduction to Quality
Control."
Therefore, it may be 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 bereferred 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.
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Cause and Effect Diagrams are useful in identifying
and isolating the cause, or the major causes, of a
problem. This diagram lists the problem at one end ofa horizontal line. Diagonal branches are drawn from
this line for each major category of possible causes.
More specific, contributory causes are added to the
branch for each category.
Whatever name you choose, remember that the
value of the fishbone diagram is to assist teams incategorizing the many potential causes of problems or
issues in an orderly way and in identifying root
causes.
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When should a fishbone diagram be used?Does the team...
Need to study a problem/issue to determine the
root cause?
Want to study all the possible reasons why a process
is beginning to have difficulties, problems, or
breakdowns?
Need to identify areas for data collection?Want to study why a process is not performing
properly or producing the desired results?
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How is a fishbone diagram constructed?Basic Steps:
1. Draw the fishbone diagram.
2. List the problem/issue to be studied in the "head of the
fish".3. Label each ""bone" of the "fish". The major categories
typically utilized are:
The 4 Ms:
Methods, Machines, Materials, ManpowerThe 4 Ps:
Place, Procedure, People, PoliciesThe 4 Ss:
Surroundings, Suppliers, Systems, Skills
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Note: You may use one of the four categories suggested,
combine them in any fashion or make up your own. The
categories are to help you organize your ideas.4. Use an idea-generating technique (e.g., brainstorming)
to identify the factors within each category that may be
affecting the problem/issue and/or effect being studied.The team should ask... "What are the machine-issues
affecting/causing..."5. Repeat this procedure with each factor under the
category to produce sub-factors. Continue asking, "Why is
this happening?" and put additional segments each factor
and subsequently under each sub-factor.
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6. Continue until you no longer get useful information
as you ask, "Why is that happening?"7. Analyze the results of the fishbone after team
members agree that an adequate amount of detail
has been provided under each major category. Do this
by looking for those items that appear in more than
one category. These become the 'most likely causes".8. For those items identified as the "most likelycauses", the team should reach consensus on listing
those items in priority order with the first item being
the most probable" cause.
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Example of a Fishbone or Cause and Effect Diagram
http://www.mindtools.com/pages/article/Cause-Effect-Diagram-Example-3.htm -
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Matrix Diagram or Quality
Function Deployment
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The matrix diagram or quality function deployment
shows the relationship between two, three or fourgroups of information. It also can give information
about the relationship, such as its strength, the roles
played by various individuals or measurements.
Six differently shaped matrices are possible: L, T, Y,
X, C and roofshaped, depending on how many
groups must be compared.
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When to Use Each Matrix Diagram Shape
In the examples, matrix axes have been shaded to
emphasize the letter that gives each matrix its name.
An Lshaped matrix relates two groups of items to
each other (or one group to itself).
A Tshaped matrix relates three groups of items:
groups B and C are each related to A. Groups B and Care not related to each other.
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A Yshaped matrix relates three groups of items.
Each group is related to the other two in a circularfashion.
A Cshaped matrix relates three groups of items
all together simultaneously, in 3-D.
An Xshaped matrix relates four groups of items.
Each group is related to two others in a circular
fashion.
A roofshaped matrix relates one group of itemsto itself. It is usually used along with an L or T
shaped matrix.
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L-shaped 2 groups A B (or A A)
T-shaped 3 groups B A C but not B C
Y-shaped 3 groups A B C A
C-shaped 3 groups All three simultaneously (3-D)
X-shaped 4 groups A B C D A but not A C
or B D
Roof-
shaped
1 group A A when also A B in L or T
Table 1: When to use differently-shaped matrices
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Frequently Used Matrix Diagram Symbols
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The L shape and T shape matrix are the most
commonly used matrix diagrams. Matrix consists ofrows and columns. The columns are used for
representing sub-categories of one variable and the
rows represent sub-categories of the second
variable. These two variables should have a
relationship. The matrix brings down the correlation
between the two variables.
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Steps involved in a Matrix Diagram
1.Select the problem.
2.Form a team with 4-5 people.
3.Choose a facilitator for the coordination of the teamsactivities.
4.Determine the product or process variables to be studied.
5.Decide on the matrix shape based on task.
6.Place the information in the matrix.
7.Draw the lines of the matrix.
8.Determine the symbols to be utilized for representing degree
of relationship between the variables and also include a
legend for symbol definitions.
9.Enter the symbols into the correct cells depending on their
relationships.
10.Analyze.
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The advantage of a matrix diagram is that ithelps in presenting complex information in easily
understandable form. It is important to study and
understand the relationships for the decision making
process. This will help clarify the relationship between
factors involved.
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Scatter Plot
Diagram
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The scatter diagram graphs pairs of numerical
data, with one variable on each axis, to look for a
relationship between them. If the variables arecorrelated, the points will fall along a line or curve.
The better the correlation, the tighter the points will
hug the line.
When to Use a Scatter Diagram
When you have paired numerical data.
When your dependent variable may have multiple
values for each value of your independent variable.
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When trying to determine whether the two variables
are related, such as
When trying to identify potential root causes ofproblems.
After brainstorming causes and effects using a
fishbone diagram, to determine objectivelywhether a particular cause and effect are related.
When determining whether two effects that
appears to be related both occur with the samecause.
When testing for autocorrelation before
constructing a control chart.
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Scatter Diagram Procedure
1. Collect pairs of data where a relationship is suspected.
2. Draw a graph with the independent variable on thehorizontal axis and the dependent variable on the vertical
axis. For each pair of data, put a dot or a symbol where
the x-axis value intersects the y-axis value. (If two dots fall
together, put them side by side, touching, so that you can
see both.)
3. Look at the pattern of points to see if a relationship is
obvious. If the data clearly form a line or a curve, you may
stop. The variables are correlated. You may wish to use
regression or correlation analysis now. Otherwise,
complete steps 4 through 7.
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4. Divide points on the graph into four quadrants. If
there are X points on the graph,
1.Count X/2 points from top to bottom and draw a
horizontal line.
2.Count X/2 points from left to right and draw a
vertical line.
3.If number of points is odd, draw the line through
the middle point.
5. Count the points in each quadrant. Do not count
points on a line.
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6. Add the diagonally opposite quadrants. Find the
smaller sum and the total of points in all quadrants.
A = points in upper left + points in lower rightB = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
7. Look up the limit for N on the trend test table.
1.If Q is less than the limit, the two variables are related.
2.If Q is greater than or equal to the limit, the pattern
could have occurred from random chance.
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Scatter Diagram Example
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Scatter Diagram Considerations:
Even if the scatter diagram shows a relationship, do notassume that one variable caused the other. Both may be
influenced by a third variable.
When the data are plotted, the more the diagram resembles
a straight line, the stronger the relationship.If a line is not clear, statistics (N and Q) determine whether
there is reasonable certainty that a relationship exists. If the
statistics say that no relationship exists, the pattern could
have occurred by random chance.
If the scatter diagram shows no relationship between the
variables, consider whether the data might be stratified.
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If the diagram shows no relationship, consider
whether the independent (x-axis) variable has beenvaried widely. Sometimes a relationship is not
apparent because the data dont cover a wide
enough range.Think creatively about how to use scatter diagrams
to discover a root cause.
Drawing a scatter diagram is the first step in looking
for a relationship between variables.
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Lessons Learned:
When we have a serious problem, it's important to
explore all of the things that could cause it, before we start tothink about a solution. That way we can solve the problem
completely, first time round, rather than just addressing part
of it and having the problem run on and on. This is where the
problem analysis tool comes out. It is of major importancewith regard to solving problems within an organization, group
or team. After all discussion and clarification of the tools, all
problems and decision making will be much easier to deal and
convenient to use. It is important to determine whether thedifferent groups of people perceive the problem in the same
way in order for them to utilize the appropriate tool in
acquiring possible solutions.