Tools for
Problem
Solving &
ANALYSIS
The QC Tools are simple
statistical tools used for
problem solving. These
tools
were
either
developed in Japan or
introduced to Japan by
the Quality Gurus such
as Deming and Juran.
In terms of importance,
these are the most useful.
Kaoru
Ishikawa
has
stated that these 7 tools
can be used to solve 95
percent of all problems.
QC TOOLS
The problems you face can be large or small, simple or complex, and
easy or difficult to solve. Regardless of the nature of the problems, a
fundamental part of every employee’s role is finding ways to solve
them. Having tools to solve problems and being a confident problem
solver is important to your success. Problem solving tools are
determined by the requirements of the problem and the amount of
time to solve the problem. There are four basic steps in problem
solving regardless of size or complexity:
1. Defining the problem
2. Generating alternatives
3. Evaluating and selecting alternatives
4. Implementing solutions
Objectives of this training
 To explain various tools that support deep analysis of problem
solving.
 Explain how the QC tools Support in decision making after analysis,
 Update on the best proven tools in quality.
Proven
Tools for
industrial
problem
solving and
Analysis
The 7 QC Tools are simple statistical tools used for problem solving. These tools were either
developed in Japan or introduced to Japan by the Quality Gurus such as Deming and Juran. In
terms of importance, these are the most useful. Kaoru Ishikawa has stated that these 7 tools can
be used to solve 95 percent of all problems. These tools have been the foundation of Japan's
astomishing industrial resurgence after the second world war.
The following are the 7 QC Tools :
1.
2.
3.
4.
5.
6.
7.
Pareto Diagram
Cause & Effect Diagram
Histogram
Control Charts
Scatter Diagrams
Graphs
Check Sheets
1
QC Tools
Fishbone Diagram
The symptom or result or
effect for which one wants to
find causes is put in the box
on the right.
Why
The lighter boxes at the end of
the large bones are main
groups in which the ideas
are classified.
The Fishbone Diagram also referred to as the "Ishikawa
diagram," because Kaoru Ishikawa developed it, and the
"fishbone diagram," because the complete diagram resembles
a fish skeleton. The diagram illustrates the main causes and
sub causes leading to an effect (symptom). It is a team
brainstorming tool used to identify potential root causes to
problems. Because of its function it may be referred to as a
cause-and-effect diagram. In a typical Fishbone diagram, the
effect is usually a problem needs to be resolved, and is placed
at the "fish head".
The causes of the effect are then laid out along the "bones",
and classified into different types along the branches. Further
causes can be laid out alongside further side branches. So the
general structure of a fishbone diagram is presented below.
Why
MAN
GAUGE
Component
Locking
The causes and its factors
are identified and entered as
branches to these main
groups.
Insufficient
power
Why
Method of
Alignment
Method of
Inspection
The Sub reasons or Sub
factors are linked to the
factors.
External
METHOD
Man
Materials
MATERIAL
Training
Availability
Expertise
Quality
Delivery
Purchase
Unable to complete
Project on time
Multi Use
Utilization
Approval
Availability
Performance
Maintenance
Availability
Funds
Methods
Machines
2
QC Tools
Pareto Analysis
Pareto Analysis is a statistical technique in
decision making that is used for the selection of a
limited number of tasks that produce significant
overall effect.
It uses the Pareto Principle (also know as the
80/20 rule) the idea that by doing 20% of the work
you can generate 80% of the benefit of doing the
whole job.
In quality improvement, a large majority of
problems (80%) are produced by a few key
causes (20%). This is also known as the vital few
and the trivial many.
The value of the Pareto Principle for a
Black belt manager is that it reminds
you to focus on the 20% of things that
matter. Of the things you do during your
project, only 20% are really important.
Pareto Diagram is a tool that arranges items in
the order of the magnitude of their contribution,
thereby identifying a few items exerting maximum
influence. This tool is used in SPC and quality
improvement for prioritising projects for
improvement, prioritising setting up of corrective
action teams to solve problems, identifying
products on which most complaints are received,
identifying the nature of complaints occurring
most often, identifying most frequent causes for
rejections or for other similar purposes.
Dr.Juran suggested the use of this principle to quality control for separating the
"vital few" problems from the "trivial many" now called the "useful many".
3
QC Tools
What is the shape of your data?
Knowing the shape of your data is as
significant as the measures like Mean,
Median etc. The shape of the data set
helps in identifying any obvious errors
and outliers that may be removed and
the measures recomputed. The shape
also helps in determining the spread
in the data. An important aspect of the
description of a variable is the shape
of its distribution, which tells you the
frequency of values from different
ranges of the variable. A data analyst
is interested in knowing how well the
distribution can be approximated by
the normal distribution. A simple study
of the shape gives a fair idea about
the datas approximation to normality.
Target
3.75 mm
Histogram
0.03 mm
USL:3.78
LSL:3.72
Histograms or Frequency Distribution Diagrams are bar charts showing the
distribution pattern of observations grouped in convenient class intervals and
arranged in order of magnitude. Histograms are useful in studying patterns of
distribution and in drawing conclusions about the process based on the
pattern.
Target
The Histogram is normal if the highest frequency is in the central group and
there is symmetrical tapering on either side of the central group. The natural or
normal distribution would indicate that the process being studied is under
control. A Histogram with an unnatural pattern may indicate that there is
possibly something unusual with the process, but is not an evidence of a
process being out of control. For instance a Histogram depicting the
distribution of age of all citizens will not peak at the centre. It will start with a
cliff tapering gradually till around the life expectancy then dropping a little
faster and once again tapering into along tail.
Upon studying a histogram the following can be immediately
inferred.




Where is the process output concentrated?
What is the spread in the process?
Is the process performing within specification limits?
What are the outliers in the process and how to set
controllable limits?
 If action needs to be taken on the process, what action is
appropriate?
 Is the assumption on the distribution of the variable correct?
0.03 mm
USL:3.78
LSL:3.72
4
QC Tools
Stage 5 Defects
Correlation
When solving a problem or analyzing a situation one 100
needs to know the relationship between two
variables. A relationship may or may not exist
75
between two variables. If a relationship exists, it may
be positive or negative, it may be strong or weak
50
and may be simple or complex. A tool to study the
relationship between two variables is known as
Scatter Diagram. A relation expressed in correlation
10
coefficient is between -1 and +1. The extremes
mean high correlation or relation ship
TOTAL
MADE
FIRST
TIME
PASSE
D
TOTAL
REJEC
TED
REJEC
TION
IN PPT
SHAFT
DAMA
GE
BINDI
NG
R2=0.84
20
FOULI
NG
30
OBSTR
UCTIO
N
Stage
3 Defects
40
Non
Unifor
m air
gap
FAN
BEND/
WOBB
LING
BRUS
H
NOISE
TOTAL MADE
FIRST TIME
PASSED
0.96
TOTAL REJECTED
0.51
0.23
REJECTION IN PPT
-0.05
-0.33
0.83
SHAFT DAMAGE
0.49
0.53
0.13
-0.19
BINDING
0.35
0.28
0.35
0.14
-0.10
FOULING
0.36
0.30
0.39
0.20
0.04
0.68
OBSTRUCTION
0.56
0.57
0.20
-0.15
0.13
0.73
0.58
Non Uniform air gap
0.62
0.55
0.43
0.11
0.54
0.14
-0.01
0.51
FAN
BEND/WOBBLING
0.19
-0.02
0.68
0.68
0.04
-0.18
0.08
-0.44
-0.03
BRUSH NOISE
-0.29
-0.52
0.57
0.87
-0.18
-0.09
-0.06
-0.53
-0.16
0.64
BEARING NOISE
0.21
0.21
0.07
-0.04
-0.17
-0.32
-0.01
-0.05
-0.06
0.24
-0.15
When solving a problem or analysing a situation one
needs to know the relationship between two variables.
A relationship may or may not exist between two variables.
If a relationship exists, it may be positive or negative, it
may be strong or weak and may be simple or complex.
A tool to study the relationship between two variables is
known as Scatter Diagram.
It consists of plotting a series of points representing
several observations on a graph in which one variable is
on X-axis and the other variable in on Y-axis. If more than
one set of values are identical, requiring more points at the
same spot, a small circle is drawn around the original dot
to indicate second point with the same values. The way the
points lie scattered in the quadrant gives a good indication
of the relationship between the two variables.
5
QC Tools
Component replacement method:
Component
replacement
Use this method to find the sub system that contributes to the
problem and also to identify the source of this problem.
Replace subcomponents from good with bad and find the subsystem
that contributes to the problem.
Component search is part of statistical engineering, as developed by Shainin, is a contrast based
approach to problem solving. Statistical engineers ask what's different rather than what's wrong.
They look for the largest source of variation, not all possible causes. They avoid identifying lists
of potential variables until the convergent process has substantially narrowed the possibilities.
Dorian Shainin … has given us DOE tools that can diagnose and greatly reduce variation,
leading us beyond zero defects, beyond the milestone of Cpk of 2.0, to near zero
variability. These tools are:
• Simple – understood by engineers and line workers alike. The mathematics involved
are unbelievably – elementary!
• Logical – based on common sense.
• Practical – easy to implement – in production, in design, with suppliers.
• Universal in scope – applicable in a wide range of industries, big and small, processintensive as well as assembly-intensive.
• Statistically powerful – in terms of accuracy, with no violations of statistical
principles.
• Excellent in terms of results – with quality gains not in the inconsequential range of
10-50% improvement but in the 100-500% range!”
Consider component search on an electrical part with several subcomponents, by swapping
the good subcomponents with bad parts and also by replacing bad ones with good
subcomponents the results should vary based on the output. This should also be repeated on
many samples.
The Shainin methods look for the "Big Red X" as the main root cause of product
deficiencies. They help to identify the failed part in a few iterative steps, so that the
failure can be fixed quickly with minimum cost.
6
Why?
QC Tools
Why?
Bad quality milk
Bad quality milk
5 Whys
Milk gone off
Milk gone off
Milk gone off
Milk gone off
When something goes wrong,
we tend to see it as a crisis and
seek to blame. A better way is to
see it as a learning opportunity.
Not in the existential sense of
general self-improvement.
Instead, we can use the
technique of asking why five
times to get to the root cause of
the problem.
Why?
Local store closed
Local store closed
Why?
Fridge Cold
Fridge Cold
etc.
etc.
Can't go to store
Can't go to store
Large store too far
Large store too far
No Milk in Fridge
No Milk in Fridge
The 5-Why is a useful exercise
to track a single line of cause
and effect but it seems to lead to
a causal factor rather than a root
cause.
Housemates
Housemates
finished milk
finished milk
No Money to buy
No Money to buy
milk
milk
To eat cereal
To eat cereal
To feed cat
To feed cat
Rent too high
Rent too high
Too many debts
Too many debts
Insufficient Salary
Insufficient Salary
The choice faced by people trying to solve problems is: HOW MUCH EFFORT IS NEEDED TO
FIND A REAL, EFFECTIVE SOLUTION TO A PROBLEM? IS IT WORTH MY TIME?
My point is that 5-Whys are EASY and easy-to-understand but often don’t get us to an effective
solutions. Thus no matter how easy the technique is, most people are wasting their time but they
THINK they are doing effective analysis. What they are really doing is trying solutions and seeing
what works.
But I think that it could be applied to 5-Whys. People have activity (they are asking questions) but
that doesn’t mean that the questions are helping them understand the problem and develop
effective solutions. Instead, they are guiding the questions to get to answers THEY ALREADY
KNOW. They then apply these answers which may work or which may appear to work (because the
incident doesn’t repeat in the near-term
Corrective actions:
bring the site back up remove the bad code
help so-and-so understand why his code
doesn't work as written train so-and-so in the
principles of TDD change the new engineer
orientation to include TDD.
7
QC Tools
Process Mapping
Process mapping is a tool that is used to understand, analyse and
document processes and activities in an organisation and assist in
identifying opportunities for improvement. A proper process map is like a
strong foundation for six sigma project and to be successful. A process
map displays the sequential steps involved in converting a specific input
into the required output,
A Map is a visual representation for the team leader’s or an entire team’s thoughts, ideas and
questions relative to accomplishing the project goal. It should be one of the first tools employed
when starting any Six Sigma or process improvement project. The Map presents a structure of
information and helps a team progress through the DMAIC process. It is a living document that will
change throughout the project and has no set format. The process map can be used to drive
specific actions and select the Six Sigma tools that should be employed. early in a project is it
ensures that nothing is left out or missed. It is an effective tool for ensuring all potential questions
and issues of a project have been both identified and addressed from the beginning of a project to
completion. The following are the steps in development of a process map.
Start
Marking
out
Cutting
to
Size
Testing
Review
Ship
Ship
Stop
Step 1: Define the Project Goal(s)
First and foremost, a team needs to clearly define the goal. What is the team trying to
accomplish? Is it a problem that needs to be solved? Is it a potential opportunity for growth that
needs to be explored? By defining the goal, the team also will define the project scope. This is
essential to do early on in a project. the scope, includes a problem statement, objective,
benefits, team members, process owner and Champion) is very helpful in this step, as it should
contain the goal or problem statement of the project.
Eg: “The receipt and processing of delivered materials takes too much time.”
Step 2: List the Knowns and Unknowns
For this step, it is most helpful to simply create two columns – one for what the team knows
and one for what the team does not know. It might be surprising how much information is
known, but even more surprising how much the team does not know.
Information can include, but is not limited to metrics, times, costs, issues, potential barriers,
points-of-contact, current problems, customer requirements, outputs, inputs, process steps,
quantities and locations.
Knowing pertinent information and data in the initial stages is important; however, equally
important is realizing what data the team will need to research.
8
QC Tools
Process Mapping
Step 3: Ask DMAIC Questions and ‘Grouped’ Questions
This step coincides closely with the previous step. Team members will recognize that their
unknowns (from Step 2) and questions from this step are very similar. The main difference is the
approach. Using two separate approaches allows very different pieces of information and questions
to surface. In the previous step, the team is stating inquiries from the perspective that they simply
do not know a vital piece of information. In this step, they are asking questions from both the
DMAIC approach, as well as a grouped approach.
First, ask questions from the categorical perspectives of DMAIC: Define, Measure, Analyze,
Improve and Control. These will be the five areas into which all questions will be categorized. It is
important to ask as many questions as possible – this is really a brainstorming exercise and no
question is a bad question.
A MAP should include, but is not limited to:
Next, the team needs
to ask questions from
the perspective of
groups that are within
or affect the process











The project goal(s) or problem statement(s)
Specific areas/parts of a process to be analysed
Any issues or questions to address
What is known about those issues or questions
What is not known about those issues or
questions
Initial assumptions about each issue or
question.
What data or information is needed
Potential barriers reaching the project goal
Interconnections between each
part/issue/question
Potential Six Sigma tools to be used
When creating a MAP, the only wrong piece of
information is the one left out.
9
QC Tools
Process Mapping
Step 4: Sequence and Link the Questions
Now it all comes together. Sequence questions below the problem
statement (or goal) and flow them down. Additionally, link questions
that are related to each other. The team members will find in this step
that they will generate many additional questions.
10
STEP 5: Identify Possible Tools to Be Used
QC Tools
Process Mapping
Finally, the project team should identify the potential Six Sigma tools to
be used to answer the questions posed. The most effective way to
perform this step is to create a four-column matrix, as illustrated in the
table below. It should have a column for the question, the tool or
method, who is responsible, and the due date.
And with this table, the TMAP process is complete, and the Six Sigma
project is off to a strong start.
Matrix for Identify Potential Six Sigma Tools/Methods
Question
Tool/Method
How long and how many people
does the transportation steps
take?
Value Stream Map
How long and how many people
does the process steps take?
Value Stream Map
Where are our failure modes?
Person
Responsible
Due Date
FMEA
How is the material inspected?
MSE
Percentage of small packages
versus large packages?
Data Analysis
Another common format for a MAP is using a Mind Map or a relationship flow as illustrated in the
following process flow. This format often works better for processes that have many links. The fivestep process can still be used to create it. Format is not significant as long as the MAP helps the
team in achieving its objective of a successful Six Sigma project. This approach gives a high level
view of projects and processes in hand, also supports in decision making for management.
11