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7 QC TOOLS
The term “7 QC tools for QC” is name after the 7 tools of the famous
warrior , Benkai. Benkai owned 7 weapons, which he used to win all his
battles. Similarly, from my own experience, you will find that you will able to
solve 95% of the problems around you if you wisely use the 7 tools of QC.”
ISHIKAWA KAORU, Professor Emeritus, University of Tokyo.
7 Quality Tools
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Introduction
In 1950, the Japanese Union of Scientists and Engineers (JUSE) invited
legendary quality guru W. Edwards Deming to go to Japan and train hundreds of
Japanese engineers, managers and scholars in statistical process control.
Deming also delivered a series of lectures to Japanese business managers on the
subject, and during his lectures, he would emphasize the importance of what he
called the "basic tool" that were available to use in quality control.
One of the members of the JUSE was Kaoru Ishikawa, at the time an associate
professor at the University of Tokyo. Ishikawa had a desire to 'democratise
quality': that is to say, he wanted to make quality control comprehensible to all
workers, and inspired by Deming’s lectures, he formalised the Seven Basic Tools
of Quality Control.
Ishikawa believed that 90% of a company’s problems could be improved using
these seven tools, and that –- with the exception of Control Charts -- they could
easily be taught to any member of the organisation. This ease-of-use combined
with their graphical nature makes statistical analysis easier for all.
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The Basic Seven (B7)
Tools of Quality
A PowerPoint Training Presentation
"As much as 95% of quality related problems in the factory can be
solved with seven fundamental quantitative tools." - Kaoru
Ishikawa
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What are the Basic Seven Tools of
Quality?
1 – Fishbone/Ishikawa Diagrams
2 - Histograms
3 - Pareto Analysis
4 - Flowcharts
5 - Scatter Plots
6 - Run Charts
7 - Control Charts
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Where did the Basic Seven come
from?
Kaoru Ishikawa
Known for “Democratizing Statistics”
The Basic Seven Tools made statistical analysis less
complicated for the average person
Good Visual Aids make statistical and quality control
more comprehendible.
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The Basic Seven (B7)
Tools of Quality
1] Fishbone Diagrams
No statistics involved
Maps out a process/problem
Makes improvement easier
Looks like a “Fish Skeleton”
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Constructing a Fishbone Diagram
Step 1 - Identify the Problem
Step 2 - Draw “spine” and “bones”
Example: High Inventory Shrinkage at local Drug Store
Shrinkage
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Constructing a Fishbone Diagram
Step 3 - Identify different areas where problems may
arise from
Ex. : High Inventory Shrinkage at local Drug Store
Shrinkage
employees
shoplifters
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Constructing a Fishbone Diagram
Step 4 - Identify what these specific causes could be
Ex. : High Inventory Shrinkage at local Drug Store
Shrinkage
shoplifters
Anti-theft tags poorly designed
Expensive merchandise
out in the open
No security/
surveillance
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Constructing a Fishbone Diagram
Ex. : High Inventory Shrinkage at local Drug Store
Shrinkage
shoplifters
Anti-theft tags poorly designed
Expensive merchandise out in the
open
No security/ surveillance
employees
attitude
new
trainee
training
benefits practices
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Constructing a Histogram
Use range to estimate beginning and
end
Calculate the width of each column by
dividing the range by the number of
columns
Range
# of Columns
= Width
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Acme Pizza ExampleMean = 2.032258
Max = 7
Min = 0
Range = 7
Question
For 7 columns what would the width be?
Range/Columns=7/7=1 slice
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Pak Mat Pizza Example
33
65
8
12
0 0 1
0
10
20
30
40
50
60
70
1 2 3 4 5 6 7
Slices of Pizza
Histogram
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Constructing a Histogram
How is this helpful to Pak Mat?
2 slices of pizza most common order placed
Distribution of sales useful for forecasting
next Thursday’s late night demand
If you were an Pak Mat manager how could
you apply this information?
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The Basic Seven (B7)
Tools of Quality
3] Pareto Analysis
Very similar to Histograms
Use of the 80/20 rule
Use of percentages to show importance
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Pak Mat Pizza (part 2)
The completed Pareto Analysis results in the following graph:
0
10
20
30
40
50
60
70
1 2 3 4 5 6 7
Slices of Pizza
2 1 4 3 7 5 6
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Pak Mat Pizza (part 2)
Critical Thinking
How does the Pareto Analysis differ
from the Histogram?
How can this be a useful tool to the Pak
Mat boss?
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The Basic Seven (B7)
Tools of Quality
4] Flowcharts
A graphical picture of a PROCESS
Process Decision
The process flow
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Pak Mat Pizza Example (Flowchart)
Window Take Customer Money?
(start) Order
Get Pizza
Lockup
Put More in
Oven 2 Pies
Available?
Time
to close?
Take to Customer
no
yes
no
yes
no
yes
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How can we use the flowchart to analyze
improvement ideas from the Histogram?
Window Take Customer Money?
(start) Order
Get Pizza
Lockup
Put More in
Oven 2 Pies
Available?
Time
to close?
Take to Customer
no
yes
no
yes
no
yes
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Want some practice?
Make a flowchart for:
Taking a shower
Cooking dinner
Driving a car
Having a party
Creating a Flowchart
Any other processes you can think of?
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The Basic Seven (B7)
Tools of Quality
5] Scatter Plots
2 Dimensional X/Y plots
Used to show relationship between
independent(x) and dependent(y)
variables
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Pak Mat Pizza (Scatter Diagram)
Minutes Cooking Defective Pies
10 1
45 8
30 5
75 20
60 14
20 4
25 6
In this simple example, you can find the existing
relationship without much difficulty but…
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Scatter Diagrams
0
5
10
15
20
25
0 20 40 60 80
•Easier to see
direct relationship
Time Cooking
(minutes)
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Scatter Diagrams
As a quality tool
What does this tell Pak Mat
management about their processes?
Improvements?
0
5
10
15
20
25
0 20 40 60 80
Time Cooking (minutes)
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The Basic Seven (B7)
Tools of Quality
6] Run charts
Time-based (x-axis)
Cyclical
Look for patterns
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Run Charts
8 9 10 11 12 1 2 3
4
8 9 10 11 12 1 2 3
4
8 9 10 11 12 1 2 3
4PM- AM PM- AM PM- AM
Thursday
Week 1
Thursday
Week 2
Thursday
Week 3
Slices/hour
Time
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The Basic Seven (B7)
Tools of Quality
7] Control Charts
Deviation from Mean
Upper and Lower Spec’s
Range
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Control Charts
Pak Mat Pizza Management wants to get in on the control chart action
•Average Diameter = 16 inches
•Upper Limit = 17 inches
•Lower Limit = 15 inches
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Acme example Control Charts
Upper Limit
17 inches
Lower Limit
15 Inches
Small Pie
X
16
inches=
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Pak Mat example #50
Control Charts
•Pies within specifications were acceptable
•One abnormally small pie is “uncommon”
•Should be examined for quality control
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Summary
Basic Seven Tools of Quality
Measuring data
Quality Analysis
“Democratized statistics”
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Bibliography
Foster, Thomas. Managing Quality. An Integrative Approach.
Upper Saddle River : Prentice Hall, 2001.
Stevenson, William. “Supercharging Your Pareto Analysis.”
Quality Progress October 2000: 51-55.
“Dr Kaoru Ishikawa.” Internet
“http://www.dti.gov.uk/mbp/bpgt/m9ja00001/m9j
a0000110.html.” 16 February 2001.
“Chemical and Process Engineering.” Internet.
“http://lorien.ncl.ac.uk/ming/spc/spc8.htm.” 17 February 2001.