Measurement System Analysis (MSA) course is essential for successful Six Sigma DMAIC and DFSS projects. It is also key for implementation of SQC, and efficient process management. Reliable measurement processes are critical to the success of any effort dependent on measurement data and process analysis, including Six Sigma DMAIC improvement projects, DFSS project, SPC, SQC, Supplier Quality, and business process management and continuous improvement. Without validation that measurements are accurate, repeatable with multiple measurements by the same person, reproducible from person to person (gage Repeatability and Reproducibility or gage R&R), all conclusions are suspect, and process management is therefore fragile and ineffective. Organizations typically focus on measurement accuracy and calibration, but this course also emphasizes the essential elements of reliable measurement procedures.

1. Measurement
System
ANALYSIS
Measurement systems
Analysis is a decision
making process on the
measuring equipment's
usability in inspection of
the quality characteristic.
It evaluates if a
measurement system is
suitable for a specific
application.

2. MSA
Objectives of this training Is your measuring equipment correct?
To explain various sources of
measurement system uncertainty.
Assessment of linearity, stability,
repeatability, and reproducibility of a
Measurement process ( Gage R and R)
“Inaccurate measurements may lead to false
signals on control charts.”
Support in setting up a measurement and
Calibration system. is a true statement and In the presence of
significant error in the measurement process, a
capable process may be confused with an
incapable process.

3. MSA
MSA is also called Gage R and R Knowledge of variation is one of the most
powerful tools a company could apply in the
quest for improvement.Gage R&R Repeatability and
reproducibility Studies are the most
widely used techniques for evaluating the
variation in a measurement system and
determining if the measurement system is
acceptable for use.
It is essential to know how much variation is as
a result of the measurement process.
When the major source of variation is from the
measurement process, significant time and
money can be wasted in fixing and controlling
the process.
Once a measurement system is found
acceptable, it is equally important to
institute a formal system to manage the
measurement system to ensure that it
continues to be reliable and dependable.
But first its essential to measure

4. MSA
Measurements
Measurements are defined as the
assignment of numbers to materials
and their characteristics so that it
could be controlled and their
relationship understood.
Do U know about the "five M's" that
constitute most root causes ?:
•Measurement is a process
•Measurements are done to understand
Measurements
man, machine, materials, methods,
and measurement.

5. ors stematic E
MSA
Measurement Error
Systematic Errors (or
offsets): These errors are
defined as the constant
values by which a
measurement instrument’s
readings are off from the
true or reference value
(or a master value).
Random Errors: These are
measurement errors caused by
differences among operators,
differences among the measuring
equipment, differences over time,
or the differences due to change
in the environmental
conditions….
Part to part variation
variation
Environment variation
Instrument variation
Systematic Errors
(offsets or biases)
Random Error
(Characterized by the variation)
Instrum
Environm
Operator
Measurement error

6. MSA
Purpose and Risks
Measurement system analysis helps reduce two
types of risks associated with the measurement
of a process and making decisions.
The purpose of Measurement
System Analysis is to qualify a
measurement system for use by
quantifying its accuracy, precision,
and stability • the risk of false alarm
• the risk of missed opportunities.
Risks

7. MSA
Variations?
Even when all the factors in a
measurement process are controlled,
repeated observations made during
precision measurement of any
parameter, even under the same
conditions, are rarely found to be
identical. This is because of the
inherent variation in any
measurement process due to ….
procedure stem from the fact that no
identical. Also, different methods of
would give rise to variation.
in the measurement.
Person and procedure..
Factors affecting person and
two human beings’ visual judgment is
measurement— the procedure—
Instrument..
All measuring instruments have a stated
accuracy or uncertainty. No instrument
can measure the true value of the
parameter. Thus, the accuracy or
uncertainty of the measuring
instrument contributes to the variation
Environment.
The environment plays an important
role in any process of measurement.It
might be possible to correct the effect
of a few environmental conditions, such
as temperature and height above mean
sea level, to some extent.
Work piece.
No work piece is absolutely stable.
There is always an inherent instability
in any material or substance. However
small the instability might be, this gives
rise to variation in the measurement
process.
Standard.
There are different levels of standard in
the traceability chain in order to provide
measurementtraceability. Each of
these standards, in turn, introduces
some variation. Factors affecting the
standard refer to this variation.

8. MSA
Resolution
The vernier caliper can
measure the quality
characteristics side
length, an outer and inner
diameter, and a depth.
When close tolerances are
required, measurements
are taken with a
micrometer due to its
superior accuracy over a
vernier calliper. .
Resolution
The resolution, or discrimination of the measurement device must be small
relative to the smaller of either the specification tolerance or the process spread
(variation).
As a rule of thumb, the measurement system should have resolution of at least
1/10th the smaller of either the specification tolerance or the process spread. If the
resolution is not fine enough, process variability will not be recognized by the
measurement system, thus reducing its efficiency.

9. MSA
Measurement
uncertainty
Every measurement is subject to some uncertainty. A measurement result is
only complete if it is accompanied by a statement of the uncertainty in the
measurement. Measurement uncertainties can come from the measuring
instrument, from the item being measured, from the environment, from the
operator, and from other sources.
Such uncertainties can be estimated using statistical analysis of a set of
measurements, and using other kinds of information about the measurement
process.

10. Machines
MSA
Measurement Systems There are different types of measurement
systems depending on the situation each with
its own methodology and purpose….
Coordinate Measuring
Vision Measuring Systems
Optical Measurement
Sensor Systems
Digital Scale
Form Measurement
Vibration Measures

11. MSA is part of all improvement process,
understanding measurement errors is
vital to improvement……..
MSA
The MSA Process
Where does MSA happen in a typical Process ?
People
Methods
Material
Equipment
Environment
PROCESS Product
Input Process / System Output
Accurate Measurement
using Measurement System Analysis
Identifying
Improvement
Opportunities

12. MSA
Measurement data Measurement
Variation
Stdev() is a measure
of spread ( variation)
in the data.
2
Where do errors and
uncertainties come from?
Many things can undermine a
measurement. Flaws in the
measurement may be visible or
invisible. Because real
measurements are never made
under perfect conditions, errors
and uncertainties can come
from measuring instruments and
the item being measured.

13. 2
MSA
Measurement Factors
Variations happen
due to a variety of
reasons, some of
these are listed
here….
Management: training programs,
metrology system, support of people,
support of quality management system .
Samples: materials, items to be tested,
sampling plan, sample preparation.
Process: test method, specification.
People: operators, training, education,
skill, care.
Equipment: measuring instrument,
calibration, fixturing
2

14. MSA
Total Variance
The total variation you measure using a
measuring equipment is the sum of
process and measurement variance……
How good is our
measurement
system?
Process
Variance
2
p
Measurement
Variance
2
m
Total
Variance
2
T
2
T 2
p 2
m= +
2 = Total Variance
= Part Variance
= Measurement Variance
T
2
p
2
m

15. Measurement
System
Errors are of 2 types,
one that impacts
accuracy and the other
the precision.
MSA
Measurement Errors Accuracy is closeness to the expected and
precision is the ability to be consistent to the
expected….
Accuracy:
Bias
Linearity
Stability
Precision:
Repeatability
Reproducibility

16. MSA
Accuracy vs Precision
When making any measurement, it is
normal practice to repeat the
measurement in order to ensure that
the data generated is repeatable.
The reliable measurement: It is also
important to make sure that the data
generated is reasonably accurate by
taking care to use measuring
instruments that are calibrated. Then,
when the same measurement is made
by a customer, the data should be
close to the figures generated by the
manufacturer, that is to say the data
should be reproducible. It is only then
that the data that has been generated
is considered reliable.
Accuracy Representation
When the accuracy of a
micrometer with a range of 0-25
mm and a least count of 1 μ is
stated as ± 4 μ, it means that if
this micrometer gives a reading
of 20.255 mm, the actual or true
value of the measurand can be
20.255 mm ± 4 μ,
i.e. between 20.251 and 20.259
mm.
Precision Representation
If a micrometer is used to
measure the diameter of a steel
pin a number of times at a
certain point and the values of
20.253, 20.252, 20.250, 20.251
mm are obtained, then the
precision or the repeatability
of the measurement can be
stated as 0.003 mm
(20.253 – 20.250 mm).

17. 2
T 2
p 2
mMSA
Types of measurement
Variation
= +
2
m
Reproducibility
Repeatability,Linearity
StabilityBias

18. 2
T 2
p 2
mMSA
Variation Defined
= +Bias is the difference
between the observed
and the reference value.
The consistency of
measurements over
time
2
m
Repeatability (Equipment variation):
variation in measurementsunder
exact conditions.
Reproducibility (Appraiser variation):
variation in the average of
measurementswhen different
operators measure the same part
A measure of the
bias values through
the expected range
of measurements
Repeatability &
ReproducibilityLinearity
StabilityBias

19. MSA
Bias
The reference value, also
known as the accepted
reference value or master value,
is a value that serves as an
agreed-upon reference for the
measured values. A reference
value can be determined by
averaging several
measurements with a higher
level of measuring equipment.
Bias
ReferenceValue
Observed
Average Value
Calibration is a measurement process that assigns values to the property of an instrument relative to reference
standards or to a designated measurement process. The purpose of calibration is to eliminate or reduce bias in
the user's measurement system relative to the reference base. The most critical element of any measurement
process is the relationship between a single measurement and the reference base for the unit of measurement.
The reference base is the ultimate source of authority for the measurement unit.

20. MSA
Inference from Bias
Observed
Average Value
Bias
Bias % = Bias / Process Variation
ReferenceValue
If there is a relatively high bias examine the
following potential root causes
• Appraisers not following the measurement
procedure
• An error in measuring the Reference Value
• Instability in the measurement.
• If the SPC chart shows a trend, the
measurement device could be wearing or
calibration could be drifting.
Bias = Observed value – Reference Value
Process Variation = 6 x Standard Deviations (Sigma)

21. MSA
Linearity Observed
Average Value
Observed
Average Value
Bias2
Operating Range
250mm50mm
The measuring instrument has more bias when measuring higher values, Bias2 is
higher than Bias1…
Bias1Linearity is the
difference in the bias
values through the
expected operating
range of the gauge.

22. MSA
Stability
Stability (or drift) is the total
variation in the measurements
obtained with a measurement
system on the same master
or part when measuring a
single characteristic over an
extende time period.
Time
Stability refers to the capacity of a measurement system to produce the same values
over time when measuring the same sample. As with statistical process control
charts, stability means the absence of "Special Cause Variation", leaving only
"Common Cause Variation" (random variation).

23. MSA
Repeatability Repeatability is the variation in measurements
obtained by one appraiser with one measurement
instrument when used several times while measuring
the identical characteristic on the same part.

24. MSA
Reproducibility
Reproducibility is the
variation in the average of
the measurements made by
different appraisers using
the same measuring
instrument when measuring
the identical characteristic
on the same part
Operator skill - some measurements depend on the skill
and judgement of the operator. One person may be better
than another at the delicate work of setting up a
measurement, or at reading fine detail by eye. The use of
an instrument such as a stopwatch depends on the reaction
time of the operator.
Three operators measure the same characteristic

25. MSA
Computation
There are three methods to compute
Gage R & R:
•
•
•
Range Method
Average and Range Method
Analysis of Variation Method

26. MSA
Computation
✓ Evaluate Repeatability and Reproducibility separately
✓ Conducted typically with three appraisers and 10 parts
Steps in the Variable
Gauge Study
(Average and Range
Method)
✓ Each appraiser measure each part 3 times in random order
✓ Compute EV (equipment variation)-Repeatability
✓ Comupte AV (appraiser variation) -Reproducability
✓ Gage R&R , (R&R)² = EV² + AV²
✓ Part Variation PV
✓ Total VariationTV² = (R&R)² + PV²8
7
6
5
4
3
2
1

27. MSA
Decision making
If repeatability is large compared to reproducibility, then
•
•
•
•
The instrument needs maintenance;
The gauge should be redesigned to be more rigid;
The clamping or location for gauging needs to be improved;
There is excessive part variation.
If reproducibility is large compared to repeatability, then
• The appraiser needs to be better trained in how to use and read the gauge
instrument;
Calibrations on the gauge dial are not clear;
A fixture of some sort may be needed to help the appraiser use the gauge more
consistently.
•
•

28. MSA
Measurement Capability Index - P/T
Gauge Capability Ratio
TP/Precision to Tolerance Ratio is the % of
tolerance that is taken up by the
bothmeasurement error which includes
repeatability and reproducibility.
Best case: 10% Acceptable: 30%
Tolerance = USL - LSL
5.15*MS
Tolerance

29. MSA
Decision making
Though a gage of gagaRR
<30% is usable the target
should be to achieve <10%.
< 10% 10 - 30 % > 30%
Great
Accept
Measurement
System
Usable
May be accepted
based on cost
Not Acceptable
Measurment
System needs
Improvement
Gage Repeatability and Reproducibility

30. MSA
Sample Output
Least
CountCharacteristic Gauge TV %EV %AV %R&R
Filler neck hole dia. Vernier calipers 0.01 0.1107 35.77 72.88 81.12
Tube crown thickness Dial vernier calipers 0.02 0.1866 49.19 38.06 62.1
Tube width Dial vernier calipers 0.02 0.0365 10.71 43.83 46.87
Inlet hole dia. Vernier calipers 0.01 0.1057 86.56 20.09 88.83

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