1. IENG 451 / 452 Data Collection: 7 Tools of Ishikawa
IENG Lecture 09
Data Collection:
7 Tools of Ishikawa
5/27/2018
IENG 451 Operational Strategies
(c) D.H. Jensen

2. Ishikawa’s “Magnificent Seven” Tools
The Seven Tools are:
Histogram / Stem & Leaf Diagram
Pareto Chart
Cause & Effect (Fishbone) Diagram
Defect Concentration Diagram
Check Sheet
Scatter (Plot) Diagram
Control Chart - not covered in this course!
The tools were not invented by Ishikawa, but were very successfully put into methodical use by him
The first six are used before starting to use the seventh
They are also reused when needed to find an assignable cause
5/27/2018
IENG 451 Operational Strategies

3. Ishikawa’s Tools: Histogram
A histogram is a bar chart that takes the shape of the distribution of the data. The process for creating a histogram depends on the purpose for making the histogram.
One purpose of a histogram is to see the shape of a distribution. To do this, we would like to have as much data as possible, and use a fine resolution.
A second purpose of a histogram is to observe the frequency with which a class of problems occurs. The resolution is controlled by the number of problem classes.
5/27/2018
IENG 451 Operational Strategies

4. Histogram: Stem-and-Leaf Plot
ENGM 720: Statistical Process Control
Histogram: Stem-and-Leaf Plot 48 53 49 52 51 63 60 64 59 54 47 45 79 65 62
Divide each number into:
Stem – one or more of the leading digits
Leaf – remaining digits (may be ordered)
Choose between 4 and 20 stems
Example: 4| 5| 6| 7| 8 9 7 9 5 3 2 1 2 3 4 9 3 4 4 2 5 9
Done!
5/27/2018
IENG 451 Operational Strategies
(c) D.H. Jensen & R.C. Wurl

5. Histogram Example (Excel)
5/27/2018
IENG 451 Operational Strategies

6. Ishikawa’s Tools: Pareto Chart
80% of any problem is the result of 20% of the potential causes
Histogram categories are sorted by the magnitude of the bar
A line graph is overlaid, and depicts the cumulative proportion of defects
Quickly identifies where to focus efforts
5/27/2018
IENG 451 Operational Strategies

7. Ishikawa’s Tools: Fishbone Diagram
Cause & Effect diagram constructed by brainstorming
Identified problem at the “head”
Connects potential causes along the spine
Sub-causes are listed along the major “bones”
Man
Material
Method
Machine
Environment
5/27/2018
IENG 451 Operational Strategies

8. Cause & Effect Diagram, Cont.
The purpose of the cause and effect diagram is to obtain as many potential influencers of a process, so that the problem solving can take a more directed approach.
Material
Machine
Man
Method
Environment
Skill Level
Low RPM
Orifice Clogs
Dusty
Humidity
Poor Conductor
Attention Level
Poor Mixing
Travel Limits
Temperature
Worn Parts
Poor Vendor
Bad Paint
5/27/2018
IENG 451 Operational Strategies

9. Ishikawa’s Tools: Defect Concentration Diagram
A defect concentration diagram graphically records the frequency of a defect with respect to product location.
Obtain a digital photo or multi-view part print showing all product faces.
Operator tallies the number and location of defects as they occur on the diagram.
5/27/2018
IENG 451 Operational Strategies

10. Ishikawa’s Tools: Check Sheet
Title
Header Info: Date, Time, Location, Operator, etc.
List
of Prob
Types
Times of Problem Occurrence (periodic)
Statistics
For Prob Types
Time of Occurrence Statistics
Overall Statistics
Instructions, settings, comments, etc.
Raw Data recorded here
Check sheets are used to collect data (values or pieces of information) in a consistent manner.
List each of the known / possible problems
Record each occurrence including time-orientation.
5/27/2018
IENG 451 Operational Strategies

11. Ishikawa’s Tools: Scatter Plot
A scatter plot shows the relationship between any two variables of interest:
Plot one variable along the X-axis and the other along the Y-axis
The presence of a relationship can be inferred or ruled out, but it cannot determine if a cause and effect relationship exists Y X
5/27/2018
IENG 451 Operational Strategies

12. VSM Lab Assignment Due THU
IENG 451 / 452
VSM Lab Assignment Due THU
Create an AS-IS and a TO-BE Value Stream Map for producing a homemade pizza:
Starting point is deciding what goes on the pizza
Ending point is when you start to chew on the pizza
AS-IS map represents 1st cut process, and includes:
Process steps AND information flows
Appropriate symbols AND process data
Include storage space and material handling times, etc.
TO-BE map represents improvements from 1st cut
Document this in a similar fashion, on a separate map!
Include Value-Analysis / Time Value Map on bottom of both
Non-Value Added to Value Added time ratio (BNVA + NVA) VA
5/27/2018
IENG 451 Operational Strategies
(c) D.H. Jensen

13. IENG 451 Operational Strategies
Questions & Issues
5/27/2018
IENG 451 Operational Strategies
(c) D.H. Jensen