ASTM E2782-17 pdf free download.Standard Guide for Measurement Systems Analysis (MSA).The size of this pdf file is 2.41M.
This guide presents terminology, concepts, and selected methods and formulas useful for measurement systems analysis (MSA). Measurement systems analysis may be broadly described as a body of theory and methodology that applies to the non-destructive measurement of the physical properties of manufactured objects.
Many types of measurements are made routinely in research organizations, business and industry, and government and academic agencies. Typically, data are generated from experimental effort or as observational studies. From such data, management decisions are made that may have wide-reaching social, economic, and political impact. Data and decision making go hand in hand and that is why the quality of any measurement is important—for data originate from a measurement process. This guide presents selected concepts and methods useful for describing and understanding the measurement process. This guide is not intended to be a comprehensive survey of this topic.
Repeatability is the variation that results when a single object is repeatedly measured in the same way, by the same appraiser, under the same conditions (see Fig. 1). The term “precision” also denotes the same concept, but “repeatability” is found more often in measurement applications. The term “conditions” is sometimes combined with repeatability to denote “repeatability conditions”.
Simple Repeatability—Simple repeatability may be evaluated using at least two measurements of each of several objects by a single appraiser under identical conditions. The simplest such experiment is to use a number of distinct objects, say n, and two measurements of each object. Let y_i1 and y_i2 be the two measurements of object i. Each measurement is contaminated with a repeatability error component,