Measurement System Analysis
How-to Guide - Workbook
Version 3.1
August 2013
MSA How-to Guide
2013 Rolls-Royce plc
The information in this document is the property of Rolls-Royce plc and may not be
copied or communicated to a third party, or used for any purpose other than that for
which it is supplied without the express written consent of Rolls-Royce plc.
This information is given in good faith based upon the latest information available to
Rolls-Royce plc, no warranty or representation is given concerning such information,
which must not be taken as establishing any contractual or other commitment binding
upon Rolls-Royce plc or any of its subsidiary or associated companies.
2 | 2013 Rolls-Royce plc
Workbook Instructions
Work through each exercise in turn to check understanding. If in doubt please seek
assistance. This is not an exam and the results will not be shared with any other
person.
You can check your answers at the back of the Workbook in the Answer Booklet.
Contents
Exercise 1: Identifying Measurement Systems
Page 4
Exercise 2: Recognising Types of Data
Page 5
Exercise 3: Understanding Repeatability and/or Reproducibility
Exercise 4: Revision and Understanding Measurement
System Analysis
Page 8
Exercise 5: Operational Definitions
Page 9
Exercise 6: Understanding Where Variation is Occurring
Page 10
Exercise 7: Capturing Reasons for Less than Acceptable
MSA Studies
Page 11
Exercise 8: Minitab Analysis
Page 12
Exercise 9: Minitab Analysis
Page 13
Pages 6 - 7
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MSA How-to Guide
Exercise 1: Identifying Measurement Systems
1.1
Think about your own part of the business & try to note down 5 measurement
systems that are used. For each consider:
What is the thing being measured?
What does the measurement system comprise of (think about the
equipment, people, measurement standards and processes being used
plus any environmental factors)
How confident are you in the reliability of the data from each measurement
system?
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Exercise 2: Recognising Types of Data
2.1
For the following descriptions, identify the type of data as Continuous or Attribute
(Please tick).
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MSA How-to Guide
Exercise 3: Understanding Repeatability and/or Reproducibility
3.1
For each of the following scenarios decide: whether the problem with the
measurement system is one of repeatability or reproducibility (where the data is
continuous) or within appraiser agreement or between appraiser agreement
(where the data is attribute):
The critical dimension of a machined part is measured in-process by four
different operators. All of the operators are asked to measure a representative
sample of 10 parts from the process multiple times. All the operators are
consistent within themselves in their measurements. However the analysis
shows that two of the operators obtain different measurements compared to the
other two.
What is the data type?
What is the problem identified with this measurement system?
3.2
The Finance department check every invoice to ensure that it is accurate before
sending it to the client. Four clerks were asked to check a sample of 20
invoices, and decide whether each was accurate or not. This was then
repeated 2 days later (by the same four clerks, using the same 20 invoices).
When the results of the two sets of checks were compared, it was found that
one of the clerks reached a different conclusion on the second day than they
did on the first, for 7 of the invoices.
What is the data type?
What is the problem identified with this measurement system?
3.3
The quality department review incoming customer complaints and assign a
complaint code to each. A sample of 20 complaints letters is taken and Susan
and John (two of the quality technicians) review each of the letters and decide
which code to assign to it. The results are compared, and for 12 of the letters,
John chose a different complaint code to Susan.
What is the data type?
What is the problem identified with this measurement system?
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Exercise 3: Understanding Repeatability and/or Reproducibility
3.4
In the goods despatch area an experiment is done to check the consistency of
the package weighing methods. 1 package is weighed multiple times on each of
the three sets of scales. Whilst two of the scales consistently reach the same
result. The results for the third set of scales show a range of different weights
for the same package
What is the data type?
What is the problem identified with this measurement system?
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MSA How-to Guide
Exercise 4: Revision and Understanding Measurement System Analysis
4.1
What is the purpose of Measurement System Analysis?
..........
4.2
What is the definition of a Measurement System?
4.3
Define what is meant by the Repeatability of a Measurement System?
4.4
Define what is meant by the Reproducibility of a Measurement System?
4.5
Define what is meant by With Appraiser Agreement?
...
4.6
Define what is meant by Within Appraiser Agreement?
...
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Exercise 5: Operational Definitions
Write an operational definition for each of the following measurements.
5.1
Timing how long it takes to get to work (in minutes).
..........
...
5.2
Determining whether the appearance of a small cake is acceptable for sale
in a bakery.
..........
...
5.3
Determining the weight of a bar of chocolate (in grams)
..........
...
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MSA How-to Guide
Exercise 6: Understanding Where Variation is Occuring?
6.1
How would you interpret each of the following components of variation
graphs?
6.1
6.2
6.3
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Exercise 7: Capturing Reasons for Less than Acceptable MSA Studies
7.1
Return to your own measurement systems as noted down in exercise 1.
What potential reasons could there be for variation? Use the Cause and
Effect Diagram to help you list as many causes of measurement system
variation as you can.
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MSA How-to Guide
Exercise 8: Minitab Analysis
8.1
The Minitab worksheet Julies Gauge R&R Data 2 contains the data from the
study which Julie and her team did once the improvements had been
implemented. Analyse this data following step 4 of the workbook.
What is the % tolerance? Is this acceptable?
Review each of the graphs in turn and describe what you think it tells you
about the measurement system performance.
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Exercise 9: Minitab Analysis
9.1
The Minitab worksheet After Improvement.mtw contains the results of the
Attribute Agreement Analysis study which Tom and his team completed after
improving the measurement system. Analyse this data (reviewing both the
numerical and graphical outputs). Has the performance of the measurement
system improved, and if so by how much? Compare the before and after
results for Between Appraisers, Within Appraisers and Each Appraiser vs
Standard.
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MSA How-to Guide
Answer Booklet
The following pages show the answers to the exercises within the workbook and
should be used for reference and learning points following the completion of the
exercises.
Contents
Exercise 1: Identifying Measurement Systems
Page 15
Exercise 2: Recognising Types of Data
Page 16
Exercise 3: Understanding Repeatability and/or Reproducibility
Page 17
Exercise 4: Revision and Understanding Measurement
System Analysis
Page 18
Exercise 5: Operational Definitions
Page 19
Exercise 6: Understanding Where Variation is Occurring
Page 20
Exercise 7: Capturing Reasons for Less than Acceptable
MSA Studies
Page 21
Exercise 8: Minitab Analysis
Pages 22-23
Exercise 9: Minitab Analysis
Page 24
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Exercise 1: Identifying Measurement Systems
1.1
There is no specific answer to this question
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MSA How-to Guide
Exercise 2: Recognising Types of Data
2.1
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Exercise 3: Understanding Repeatability and/or Reproducibility
3.1
3.2
3.3
3.4
The data is continuous. Because two of the operators obtain different results
from the other two, there is a reproducibility issue.
The data is attribute. Because the results for one of the clerks differs between
the first and second set of checks, there is a within appraiser agreement issue
with that particular clerk.
The data is attribute. As Susan and John chose different complaints codes to
each other for some of the letters, there is a between appraiser agreement
issue.
The data is continuous. Because one of the sets of scales does not weigh the
same part consistently there is a repeatability issue with this particular set of
scales.
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MSA How-to Guide
Exercise 4: Revision and Understanding Measurement System Analysis
4.1
Measurement System Analysis is used to assess the ability of a measurement
system to provide good quality data.
4.2
A Measurement System is the combination of people, equipment, materials,
methods and environment involved in obtaining measurements
4.3
4.4
4.5
4.6
Repeatability assesses whether each person can measure the same item
multiple times with the same measurement device and get the same value when
measuring continuous data.
Reproducibility assesses whether different people can measure the same item
with the same measurement device and get the same value when measuring
continuous data
Within Appraiser Agreement assesses whether each person can assess the
same item multiple times using the same measurement method and get the
same result when measuring attribute data
Between Appraiser Agreement assesses whether different people can assess
the same item using the same measurement method and get the same result
when measuring attribute data
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Exercise 5: Operational Definitions
5.1
5.2
5.3
The time should be measured using a stopwatch. Before beginning the
measurement press the reset button and ensure that the display shows 00:00.
Start measuring when you close the front door of your house for the final time, by
pressing the red button on the top of the stopwatch, and stop measuring when
you arrive at your desk, by pressing the red button again. Note the time on the
stopwatch in minutes (the first 2 digits) ignoring any seconds shown. For
example, 23:47 would be recorded as 23 minutes.
The sponge cake should have risen above the top of the paper cake case, and
the cake must be a similar size and shape to the examples which are shown in
the photographs next to the quality inspection station. The icing must be of an
even colour, and, must appear to be of even thickness across the full surface of
the cake, with no sponge visible underneath the icing. There must be no icing or
other marks on the paper cake case. The cherry being used to decorate the cake
must be whole and must be in the centre of the cake.
Using a set of kitchen scales, ensure that the dial on the empty scales shows a
reading of zero by adjusting the thumbwheel at the back of the scales. Unwrap
the chocolate bar and place it gently on the middle of the scales. Allow 5 seconds
for the reading to stabilise and then note the reading to the nearest gram. If the
needle on the dial is below the nearest half gram marking, round the weight down
to the nearest gram. If the needle is above the nearest half gram marking, round
the weight up to the nearest gram.
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MSA How-to Guide
Exercise 6: Understanding Where Variation is Occurring?
6.1
We can see that the Repeat bar is tall
compared to the Part-to-Part bar,
which indicates that there is an issue
with Repeatability with one or more of
the appraisers.
6.2
We can see that the Gauge R&R and
the Repeat and Reprod bars are all
small compared to the Part-to-Part bar,
which indicates a good measurement
system.
6.3
We can see that the Reprod bar is tall
compared to the Part-to-Part bar, which
indicates that there is an issue with
Reproducibility.
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Exercise 7: Capturing Reasons for Less than Acceptable MSA Studies
7.1
There is no specific answer to this question.
Based upon delegates own work but should contain several items under each of
the main blocks. People, Method, Equipment, Materials etc.
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MSA How-to Guide
Exercise 8: Minitab Analysis
8.1
We can see from the session window that the %Tolerance is 10.51%, which
means that the measurement system is now acceptable. We can also see that the
number of distinct categories is now 27, which again indicates that the
measurement system is acceptable.
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Exercise 8: Minitab Analysis
The results of the graphical analysis are summarised in the table below.
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MSA How-to Guide
Exercise 9: Minitab Analysis
9.1
As we can see from the After results below, all of the %agreement results are
now 90% or above, which is an improvement on the results seen before. All
aspects of the measurement system are now acceptable (i.e. Within Appraisers,
Each Appraiser vs Standard and Between Appraisers all have % Agreement
>70%).
Before
After
Improvement in % agreement
Improvement in % agreement
Improvement in % agreement
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Measurement System Analysis
How-to Guide - Workbook
Change History
Revision
Date
Description of Change
Author
Owner
Approval
V3.1
20/08/2013
Guide reformatted for
SABRe
D Prodger
D Prodger
D Prodger
Document update policy
This document may be updated periodically. Major amendments will be shown as an update from one
revision number to a higher revision number (e.g. revision 1 to revision 2) and therefore the content of
the higher revision will be regarded as the latest requirements. A minor amendment will be shown as a
number change after a decimal point (e.g. revision 1.1 to revision 1.2) and therefore any of these
revisions may be regarded as the latest requirements until a major amendment is introduced
Rolls-Royce plc 2013
The information in this document is the property of Rolls-Royce
plc and may not be copied, communicated to a third party or
used for any purpose other than that for which it is supplied,
without the express written consent of Rolls-Royce plc.
While the information is given in good faith based upon the
latest information available to Rolls-Royce plc, no warranty or
representation is given concerning such information, which must
not be taken as establishing any contractual or other
commitment binding upon Rolls-Royce plc or any of its
subsidiary or associated companies.
2013 Rolls-Royce plc | 25
