Measurement systems analysis

A measurement systems analysis (MSA) is a thorough assessment of a measurement process, and typically includes a specially designed experiment 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 have variation and produce incorrect results. A measurement systems analysis evaluates the test method, measuring instruments, 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 systems.

MSA analyzes the collection of equipment, operations, procedures, software and personnel that affects the assignment of a number to a measurement characteristic. (US Department of Agriculture,pp45)

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, and destructive testing analysis. The tool selected is usually determined by characteristics of the measurement system itself.

Factors might include:

These can be plotted in a "fishbone" Ishikawa diagram to help identify potential sources of measurement variation.

ASTM has several procedures for evaluating measurement systems and test methods, including:

The American Society of Mechanical Engineers (ASME) has several procedures and reports targeted at task specific uncertainty budgeting and methods for utilizing those uncertainty estimates when evaluating the measurand for compliance to specification. They are:

The measurement systems analysis process is defined in a number of published documents including the Automotive Industry Action Group (AIAG) MSA manual, which is part of a series of inter-related documents the AIAG controls and publishes. The AIAG is a non-profit association of automotive companies founded in 1982. These manuals include:

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