Measurement Systems Analysis
Encyclopedia
A Measurement System Analysis (MSA) is a specially designed experiment
that seeks to identify the components of variation in the measurement.
Just as processes that produce a product may vary, the process of obtaining measurements and data may have variation and produce defects. A Measurement Systems Analysis evaluates the test method
, measuring instrument
s, and the entire process of obtaining measurements to ensure the integrity of data used for analysis (usually quality analysis) and to understand the implications of measurement error for decisions made about a product or process. MSA is an important element of Six Sigma
methodology and of other quality management system
s.
MSA analyzes the collection of equipment, operations, procedures, software and personnel that affects the assignment of a number to a measurement characteristic.
A Measurement Systems Analysis considers the following:
Common tools and techniques of Measurement Systems Analysis include: calibration studies, fixed effect ANOVA, components of variance, Attribute Gage Study, Gage R&R, ANOVA Gage R&R
, Destructive Testing Analysis and others. The tool selected is usually determined by characteristics of the measurement system itself.
These can be plotted in a "fishbone" Ishikawa diagram
to help identify potential sources of measurement variation.
s, including:
budgeting and methods for utilizing those uncertainty estimates when evaluating the measurand for compliance to specification.
(AIAG) is a non-profit association of automotive companies founded in 1982. These manuals include:
Experiment
An experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results...
that seeks to identify the components of variation in the measurement.
Just as processes that produce a product may vary, the process of obtaining measurements and data may have variation and produce defects. A Measurement Systems Analysis evaluates the test method
Test method
A test method is a definitive procedure that produces a test result.A test can be considered as technical operation that consists of determination of one or more characteristics of a given product, process or service according to a specified procedure. Often a test is part of an experiment.The test...
, measuring instrument
Measuring instrument
In the physical sciences, quality assurance, and engineering, measurement is the activity of obtaining and comparing physical quantities of real-world objects and events. Established standard objects and events are used as units, and the process of measurement gives a number relating the item...
s, and the entire process of obtaining measurements to ensure the integrity of data used for analysis (usually quality analysis) and to understand the implications of measurement error for decisions made about a product or process. MSA is an important element of Six Sigma
Six Sigma
Six Sigma is a business management strategy originally developed by Motorola, USA in 1986. , it is widely used in many sectors of industry.Six Sigma seeks to improve the quality of process outputs by identifying and removing the causes of defects and minimizing variability in manufacturing and...
methodology and of other quality management system
Quality management system
A quality management system can be expressed as the organizational structure, procedures, processes and resources needed to implement quality management.-Elements of a Quality Management System:# Organizational structure# Responsibilities# Methods...
s.
MSA analyzes the collection of equipment, operations, procedures, software and personnel that affects the assignment of a number to a measurement characteristic.
A Measurement Systems Analysis considers the following:
- Selecting the correct measurement and approach
- Assessing the measuring device
- Assessing procedures and operators
- Assessing any measurement interactions
- Calculating the measurement uncertaintyMeasurement uncertaintyIn metrology, measurement uncertainty is a non-negative parameter characterizing the dispersion of the values attributed to a measured quantity. The uncertainty has a probabilistic basis and reflects incomplete knowledge of the quantity. All measurements are subject to uncertainty and a measured...
of individual measurement devices and/or measurement systems
Common tools and techniques of Measurement Systems Analysis include: calibration studies, fixed effect ANOVA, components of variance, Attribute Gage Study, Gage R&R, ANOVA Gage R&R
ANOVA Gage R&R
ANOVA Gauge R&R is a measurement systems analysis technique that uses analysis of variance random effects model to assess a measurement system....
, Destructive Testing Analysis and others. The tool selected is usually determined by characteristics of the measurement system itself.
Factors affecting measurement systems
Factors might include:- Equipment: measuring instrumentMeasuring instrumentIn the physical sciences, quality assurance, and engineering, measurement is the activity of obtaining and comparing physical quantities of real-world objects and events. Established standard objects and events are used as units, and the process of measurement gives a number relating the item...
, calibrationCalibrationCalibration is a comparison between measurements – one of known magnitude or correctness made or set with one device and another measurement made in as similar a way as possible with a second device....
, fixturing, etc - People: operators, training, education, skill, care
- Process: test methodTest methodA test method is a definitive procedure that produces a test result.A test can be considered as technical operation that consists of determination of one or more characteristics of a given product, process or service according to a specified procedure. Often a test is part of an experiment.The test...
, specification - Samples: materials, items to be tested (sometimes called "parts"), sampling plan, sample preparation, etc
- Environment: temperatureTemperatureTemperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
, humidityHumidityHumidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture,...
, conditioning, pre-conditioning, - Management: training programs, metrologyMetrologyMetrology is the science of measurement. Metrology includes all theoretical and practical aspects of measurement. The word comes from Greek μέτρον , "measure" + "λόγος" , amongst others meaning "speech, oration, discourse, quote, study, calculation, reason"...
system, support of people, support of quality management systemQuality management systemA quality management system can be expressed as the organizational structure, procedures, processes and resources needed to implement quality management.-Elements of a Quality Management System:# Organizational structure# Responsibilities# Methods...
, etc
These can be plotted in a "fishbone" Ishikawa diagram
Ishikawa diagram
Ishikawa diagrams are causal diagrams that show the causes of a certain event -- created by Kaoru Ishikawa . Common uses of the Ishikawa diagram are product design and quality defect prevention, to identify potential factors causing an overall effect...
to help identify potential sources of measurement variation.
ASTM
ASTM has several procedures for evaluating measurement systems and test methodTest method
A test method is a definitive procedure that produces a test result.A test can be considered as technical operation that consists of determination of one or more characteristics of a given product, process or service according to a specified procedure. Often a test is part of an experiment.The test...
s, including:
- ASTM D4356 Standard Practice for Establishing Consistent Test Method Tolerances
- ASTM E691 Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
- ASTM E1169 Standard Guide for Conducting Ruggedness Tests
- ASTM E1488 Standard Guide for Statistical Procedures to Use in Developing and Applying Test Methods
- ASTM E2782 Standard Guide for Measurement Systems Analysis (MSA)
ASME
ASME has several procedures and reports targeted at task specific uncertaintyUncertainty
Uncertainty is a term used in subtly different ways in a number of fields, including physics, philosophy, statistics, economics, finance, insurance, psychology, sociology, engineering, and information science...
budgeting and methods for utilizing those uncertainty estimates when evaluating the measurand for compliance to specification.
- B89.7.3.1 - 2001 Guidelines for Decision Rules: Considering Measurement Uncertainty Determining Conformance to Specifications
- B89.7.3.2 - 2007 Guidelines for the Evaluation of Dimensional Measurement Uncertainty (Technical Report)
- B89.7.3.3 - 2002 Guidelines for Assessing the Reliability of Dimensional Measurement Uncertainty Statements
Auto industry
The Measurement Systems Analysis process is defined in a number of published documents including the AIAG's MSA (Measurement Systems Analysis) Manual, which is part of a series of inter-related documents the AIAG controls and publishes. The Automotive Industry Action GroupAutomotive Industry Action Group
Automotive Industry Action Group, also known as AIAG, is a not-for profit association based in Southfield, Michigan originally created to develop recommendations and a framework for the improvement of quality in the North American Automotive Industry....
(AIAG) is a non-profit association of automotive companies founded in 1982. These manuals include:
- The Failure mode and effects analysisFailure mode and effects analysisA failure modes and effects analysis is a procedure in product development and operations management for analysis of potential failure modes within a system for classification by the severity and likelihood of the failures...
(FMEA) and Control Plan Manual - The Statistical process controlStatistical process controlStatistical process control is the application of statistical methods to the monitoring and control of a process to ensure that it operates at its full potential to produce conforming product. Under SPC, a process behaves predictably to produce as much conforming product as possible with the least...
(SPC) Manual - The MSA (Measurement Systems Analysis) Manual
- The Production Part Approval Process (PPAP) Manual
Goals of MSA
- Measurement uncertaintyMeasurement uncertaintyIn metrology, measurement uncertainty is a non-negative parameter characterizing the dispersion of the values attributed to a measured quantity. The uncertainty has a probabilistic basis and reflects incomplete knowledge of the quantity. All measurements are subject to uncertainty and a measured...
- Accuracy and precisionAccuracy and precisionIn the fields of science, engineering, industry and statistics, the accuracy of a measurement system is the degree of closeness of measurements of a quantity to that quantity's actual value. The precision of a measurement system, also called reproducibility or repeatability, is the degree to which...
- Bias
- Stability
- Linearity
- RepeatabilityRepeatabilityRepeatability or test-retest reliability is the variation in measurements if they would have been taken by a single person or instrument on the same item and under the same conditions. A less-than-perfect test-retest reliability causes test-retest variability. Such variability can be caused by, for...
and ReproducibilityReproducibilityReproducibility is the ability of an experiment or study to be accurately reproduced, or replicated, by someone else working independently... - Attribute study
- Practical examples for calculating Bias, Stability, Linearity, Repeatability and reproducibility, Attribute study
See also
- MetrologyMetrologyMetrology is the science of measurement. Metrology includes all theoretical and practical aspects of measurement. The word comes from Greek μέτρον , "measure" + "λόγος" , amongst others meaning "speech, oration, discourse, quote, study, calculation, reason"...
- Measurement uncertaintyMeasurement uncertaintyIn metrology, measurement uncertainty is a non-negative parameter characterizing the dispersion of the values attributed to a measured quantity. The uncertainty has a probabilistic basis and reflects incomplete knowledge of the quantity. All measurements are subject to uncertainty and a measured...
- CalibrationCalibrationCalibration is a comparison between measurements – one of known magnitude or correctness made or set with one device and another measurement made in as similar a way as possible with a second device....
- ANOVA Gauge R&R
- Round robin testRound robin testIn experimental methodology, a round robin test is an interlaboratory test performed independently several times. This can involve multiple independent scientists performing the test with the use of the same method in different equipment, or a variety of methods and equipment...
- Verification and validationVerification and ValidationIn software project management, software testing, and software engineering, verification and validation is the process of checking that a software system meets specifications and that it fulfills its intended purpose...