TM 620
Fall 2008
Session Six Homework Solutions
Some of these questions do not have a universal answer. Therefore, the answers are written to
elicit a range of potential answers based on differing perspectives. When this is true, it is
particularly important for the student to concentrate on justifying their selected perspective.
Chapter Ten Discussion Questions
7. Describe the purpose of a Pareto chart. Describe an instance (other than the one in the book) in
which a Pareto chart could be effectively used.
A Pareto Chart is a histogram that allows the analyst to identify and prioritize potential or
real problems based upon Juran’s “80/20” rule. There are many personal and
professional examples you could select to describe.
9. What is the purpose of a cause-and-effect (Ishikawa) diagram?
Often workers spend too much time focusing improvement efforts on the
symptoms of problems rather than the causes. The Ishikawa cause and effect
diagram is a good tool to help move to lower levels of abstraction in solving
problems. The diagram looks like the skeleton of a fish: the problem being the
head of the fish, major causes being the "ribs" of the fish, and sub-causes forming
smaller "bones" off of the ribs. Figure 10-5 in the text shows an Ishikawa
diagram that was performed for a wood mill that was experiencing problems with
wobbling blades in its saws. The symptom of the problem was the wobbly blade.
The major causes were associated with machines, materials, people and methods.
Under people, it was found that workers were not properly trained. Under
machines, it was found that the blade was being setup off-center.
10. Describe the purpose of a check sheet. Describe an instance (other than the ones in the book)
in which a check sheet could be effectively used.
A check sheet is a simple mechanism that is used to gather information that can
be used to diagnose a problem. On page 303, the text uses the check sheet to
collect information that will be used to compile a histogram.
13. What is the purpose of a control chart?
A control chart provides information about a product or service that have
measurable quantities. This information can be used to detect changes in the
system.
15. What is the purpose of an affinity diagram?
An affinity tool is a brainstorming technique that will allow the team to take an
issue, break it down to component sub-issues, and enable the team to isolate the
root problems and provide solutions to them.
20. What is the purpose of a process decision program chart?
A process decision program chart is used to help brainstorm possible
contingencies or problems associated with the implementation of some program
or improvement. The tool can take the form of either an outline or a tree chart.
Chapter Ten Problems
7. Develop a histogram for the data given in the book. Develop two separate histograms for
hours of overtime and days absent. How do the data appear to be distributed?
Historgram
14
12
Frequency
10
8
6
4
2
0
0-99
100-199
200-299
300-399
400-499
3
4+
Hours of Overtime
Histogram
8
7
Frequency
6
5
4
3
2
1
0
0
1
2
Days Absent
Hours of overtime appears to be fairly normal with a small skew. Days absent
appears to be fairly uniform.
8. Using the data in Problem 7, develop a scatter plot of hours of overtime versus days absent.
Do the data overtime hours and days absent appear to be correlated?
Scatter Plot
7
6
Days Absent
5
4
3
2
1
0
0
50
100
150
200
250
300
350
400
450
500
Hours of Overtime
Yes, days absent and hours of overtime do appear to be correlated.
13. For the data in the book, develop a Pareto analysis. The letters A, B, C, D, E, and F are
problems that occur in a process. Which cause should you focus on first?
Pareto Chart
25
Frequency
20
15
10
5
0
A
B
C
D
E
F
Problem Type
We should focus on A first.
26. Complete the analysis for the prioritization matrix information be finding the final ranking.
Decision Alt.s
Machine 1
Machine 2
Machine 3
Machine 4
Criterion A
0.3
1
2
3
4
Criterion B
0.2
3
2
4
1
Criterion C
0.5
4
2
1
3
Scores
2.9
2
2.2
2.9
Final Ranking
3
1
2
3