A measurement system analysis (MSA) is a thorough assessment of a measurement process, and typically includes a specially designed

experiment An experiment is a procedure carried out to support or refute a hypothesis, or determine the efficacy or likelihood of something previously untried. Experiments provide insight into cause-and-effect by demonstrating what outcome occurs whe ...

that seeks to identify the components of variation in that measurement process. Just as processes that produce a product may vary, the process of obtaining measurements and data may also have variation and produce incorrect results. A measurement systems analysis evaluates the

test method A test method is a method for a test in science or engineering, such as a physical test, chemical test, or statistical test. It is a specified procedure that produces a test result. To ensure accurate and relevant results, a test method should b ...

measuring instrument Instrumentation is a collective term for measuring instruments, used for indicating, measuring, and recording physical quantities. It is also a field of study about the art and science about making measurement instruments, involving the related ...

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. Proper measurement system analysis is critical for producing a consistent product in manufacturing and when left uncontrolled can result in a drift of key parameters and unusable final products. MSA is also an important element of

Six Sigma Six Sigma (6σ) is a set of techniques and tools for process improvement. It was introduced by American engineer Bill Smith while working at Motorola in 1986. Six Sigma strategies seek to improve manufacturing quality by identifying and removin ...

methodology and of other

quality management system A quality management system (QMS) is a collection of business processes focused on consistently meeting customer requirements and enhancing their satisfaction. It is aligned with an organization's purpose and strategic direction ( ISO 9001:2015). ...

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 system 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 uncertainty In metrology, measurement uncertainty is the expression of the statistical dispersion of the values attributed to a quantity measured on an interval or ratio scale. All measurements are subject to uncertainty and a measurement result is complet ...

of individual measurement devices and/or measurement systems Common tools and techniques of measurement system analysis include: calibration studies, fixed effect ANOVA, components of variance, attribute gage study, gage R&R, ANOVA gage R&R, and destructive testing analysis. The tool selected is usually determined by characteristics of the measurement system itself. An introduction to MSA can be found in chapter 8 of Doug Montgomery's Quality Control book. These tools and techniques are also described in the books by Donald Wheeler and Kim Niles. Advanced procedures for designing MSA studies can be found in Burdick ''et al.'' Equipment: measuring instrument,

calibration In measurement technology and metrology, calibration is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy. Such a standard could be another measurement device of known ...

, fixturing. * People: operators, training, education, skill, care. * Process: test method,

specification A specification often refers to a set of documented requirements to be satisfied by a material, design, product, or service. A specification is often a type of technical standard. There are different types of technical or engineering specificati ...

. * Samples: materials, items to be tested (sometimes called "parts"), sampling plan, sample preparation. * Environment:

temperature Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...

humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation (meteorology), precipitation, dew, or fog t ...

, conditioning, pre-conditioning. * Management: training programs,

metrology Metrology is the scientific study of measurement. It establishes a common understanding of Unit of measurement, units, crucial in linking human activities. Modern metrology has its roots in the French Revolution's political motivation to stan ...

system, support of people, support of quality management system. These can be plotted in a "fishbone"

Ishikawa diagram Ishikawa diagrams (also called fishbone diagrams, herringbone diagrams, cause-and-effect diagrams) are causal diagrams created by Kaoru Ishikawa that show the potential causes of a specific event. Common uses of the Ishikawa diagram are produc ...

to help identify potential sources of measurement variation.

Goals

The goals of a MSA are: # Quantification of measurement uncertainty, including the accuracy, precision including

repeatability Repeatability or test–retest reliability is the closeness of the agreement between the results of successive measurements of the same measure, when carried out under the same conditions of measurement. In other words, the measurements are take ...

and

reproducibility Reproducibility, closely related to replicability and repeatability, is a major principle underpinning the scientific method. For the findings of a study to be reproducible means that results obtained by an experiment or an observational study or ...

, the stability and linearity of these quantities over time and across the intended range of use of the measurement process. # Development of improvement plans, when needed. # Decision about whether a measurement process is adequate for a specific engineering/manufacturing application.

ASTM Procedures

The

ASTM ASTM International, formerly known as American Society for Testing and Materials, is a standards organization that develops and publishes voluntary consensus technical international standards for a wide range of materials, products, systems and s ...

has several procedures for evaluating measurement systems and test methods, including: * ASTM E2782 - Standard Guide for Measurement System Analysis * 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

ASME Procedures

The

American Society of Mechanical Engineers The American Society of Mechanical Engineers (ASME) is an American professional association that, in its own words, "promotes the art, science, and practice of multidisciplinary engineering and allied sciences around the globe" via "continuing edu ...

(ASME) has several procedures and reports targeted at task-specific

uncertainty Uncertainty or incertitude refers to situations involving imperfect or unknown information. It applies to predictions of future events, to physical measurements that are already made, or to the unknown, and is particularly relevant for decision ...

budgeting and methods for utilizing those uncertainty estimates when evaluating the measurand for compliance to specification. They are: * 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

AIAG Procedures

The Automotive Industry Action Group (AIAG), a non-profit association of automotive companies, has documented a recommended measurement system analysis procedure in their MSA manual. This book is part of a series of inter-related manuals the AIAG controls and publishes, including: * The measurement system analysis manual * The

failure mode and effects analysis Failure is the social concept of not meeting a desirable or intended Goal, objective, and is usually viewed as the opposite of success. The criteria for failure depends on context, and may be relative to a particular observer or belief system ...

(FMEA) and Control Plan manual * The

statistical process control Statistical process control (SPC) or statistical quality control (SQC) is the application of statistics, statistical methods to monitor and control the quality of a production process. This helps to ensure that the process operates efficiently, ...

(SPC) manual * The production part approval process (PPAP) manual Note that the AIAG's website has a list of "errata sheets" for its publications.

References

{{reflist Measurement

Goals

ASTM Procedures

ASME Procedures

AIAG Procedures

See also

References