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A test method is a method for a test in
science Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. Modern science is typically divided into twoor threemajor branches: the natural sciences, which stu ...
or
engineering Engineering is the practice of using natural science, mathematics, and the engineering design process to Problem solving#Engineering, solve problems within technology, increase efficiency and productivity, and improve Systems engineering, s ...
, such as a physical test, chemical test, or
statistical test A statistical hypothesis test is a method of statistical inference used to decide whether the data provide sufficient evidence to reject a particular hypothesis. A statistical hypothesis test typically involves a calculation of a test statistic. ...
. It is a specified procedure that produces a test result. To ensure accurate and relevant results, a test method should be "explicit, unambiguous, and experimentally feasible.", as well as effective and reproducible. A test is an
observation Observation in the natural sciences is an act or instance of noticing or perceiving and the acquisition of information from a primary source. In living beings, observation employs the senses. In science, observation can also involve the percep ...
or
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 determines one or more characteristics of a given sample, product, process, or service, with the purpose of comparing the test result to expected or desired results. The results can be qualitative (yes/no), quantitative (a measured value), or categorical and can be derived from personal
observation Observation in the natural sciences is an act or instance of noticing or perceiving and the acquisition of information from a primary source. In living beings, observation employs the senses. In science, observation can also involve the percep ...
or the output of a precision
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 ...
. Usually the test result is the
dependent variable A variable is considered dependent if it depends on (or is hypothesized to depend on) an independent variable. Dependent variables are studied under the supposition or demand that they depend, by some law or rule (e.g., by a mathematical functio ...
, the measured response based on the particular conditions of the test defined by the value of the independent variable. Some tests may involve changing the independent variable to determine the level at which a certain response occurs: in this case, the test result is the independent variable.


Importance

In
software development Software development is the process of designing and Implementation, implementing a software solution to Computer user satisfaction, satisfy a User (computing), user. The process is more encompassing than Computer programming, programming, wri ...
,
engineering Engineering is the practice of using natural science, mathematics, and the engineering design process to Problem solving#Engineering, solve problems within technology, increase efficiency and productivity, and improve Systems engineering, s ...
,
science Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. Modern science is typically divided into twoor threemajor branches: the natural sciences, which stu ...
,
manufacturing Manufacturing is the creation or production of goods with the help of equipment, labor, machines, tools, and chemical or biological processing or formulation. It is the essence of the secondary sector of the economy. The term may refer ...
, and
business Business is the practice of making one's living or making money by producing or Trade, buying and selling Product (business), products (such as goods and Service (economics), services). It is also "any activity or enterprise entered into for ...
, its developers, researchers, manufacturers, and related personnel must understand and agree upon methods of obtaining data and making
measurement Measurement is the quantification of attributes of an object or event, which can be used to compare with other objects or events. In other words, measurement is a process of determining how large or small a physical quantity is as compared to ...
s. It is common for a
physical property A physical property is any property of a physical system that is measurable. The changes in the physical properties of a system can be used to describe its changes between momentary states. A quantifiable physical property is called ''physical ...
to be strongly affected by the precise method of testing or measuring that property. As such, fully documenting
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 ...
s and measurements while providing needed documentation and descriptions of specifications,
contract A contract is an agreement that specifies certain legally enforceable rights and obligations pertaining to two or more parties. A contract typically involves consent to transfer of goods, services, money, or promise to transfer any of thos ...
s, and test methods is vital. Using a
standardized Standardization (American English) or standardisation (British English) is the process of implementing and developing technical standards based on the consensus of different parties that include firms, users, interest groups, standards organiza ...
test method, perhaps published by a respected
standards organization A standards organization, standards body, standards developing organization (SDO), or standards setting organization (SSO) is an organization whose primary function is developing, coordinating, promulgating, revising, amending, reissuing, interpr ...
, is a good place to start. Sometimes it is more useful to modify an existing test method or to develop a new one, though such home-grown test methods should be validated and, in certain cases, demonstrate technical equivalency to primary, standardized methods. Again, documentation and full disclosure are necessary. A well-written test method is important. However, even more important is choosing a method of measuring the correct property or characteristic. Not all tests and measurements are equally useful: usually a test result is used to predict or imply suitability for a certain purpose. For example, if a manufactured item has several components, test methods may have several levels of connections: * test results of a raw material should connect with tests of a component made from that material * test results of a component should connect with performance testing of a complete item * results of laboratory performance testing should connect with field performance These connections or correlations may be based on published literature, engineering studies, or formal programs such as quality function deployment. Validation of the suitability of the test method is often required.


Content

Quality management systems usually require full documentation of the procedures used in a test. The document for a test method might include: * descriptive title * scope over which class(es) of items, policies, etc. may be evaluated * date of last effective revision and revision designation * reference to most recent test method validation * person, office, or agency responsible for questions on the test method, updates, and deviations * significance or importance of the test method and its intended use * terminology and definitions to clarify the meanings of the test method * types of apparatus and measuring instrument (sometimes the specific device) required to conduct the test * sampling procedures (how samples are to be obtained and prepared, as well as the sample size) *
safety Safety is the state of being protected from harm or other danger. Safety can also refer to the control of recognized hazards in order to achieve an acceptable level of risk. Meanings The word 'safety' entered the English language in the 1 ...
precautions * required calibrations and
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 ...
systems *
natural environment The natural environment or natural world encompasses all life, biotic and abiotic component, abiotic things occurring nature, naturally, meaning in this case not artificiality, artificial. The term is most often applied to Earth or some parts ...
concerns and considerations * testing environment concerns and considerations * detailed procedures for conducting the test * calculation and analysis of data * interpretation of data and test method output * report format, content, data, etc.


Validation

Test methods are often scrutinized for their validity, applicability, and accuracy. It is very important that the scope of the test method be clearly defined, and any aspect included in the scope is shown to be accurate and repeatable through validation. Test method validations often encompass the following considerations: *
accuracy and precision Accuracy and precision are two measures of ''observational error''. ''Accuracy'' is how close a given set of measurements (observations or readings) are to their ''true value''. ''Precision'' is how close the measurements are to each other. The ...
; demonstration of accuracy may require the creation of a reference value if none is yet available * repeatability and reproducibility, sometimes in the form of a Gauge R&R. * range, or a continuum scale over which the test method would be considered accurate (e.g., 10 N to 100 N force test) * measurement resolution, be it spatial, temporal, or otherwise * curve fitting, typically for linearity, which justifies
interpolation In the mathematics, mathematical field of numerical analysis, interpolation is a type of estimation, a method of constructing (finding) new data points based on the range of a discrete set of known data points. In engineering and science, one ...
between calibrated reference points * robustness, or the insensitivity to potentially subtle variables in the test environment or setup which may be difficult to control * usefulness to predict end-use characteristics and performance * measurement uncertainty * interlaboratory or round robin tests * other types of measurement systems analysis


See also

* Certified reference materials *
Data analysis Data analysis is the process of inspecting, Data cleansing, cleansing, Data transformation, transforming, and Data modeling, modeling data with the goal of discovering useful information, informing conclusions, and supporting decision-making. Da ...
* Design of experiments * Document management system * EPA Methods * Integrated test facility * Measurement systems analysis * Measurement uncertainty *
Metrication Metrication or metrification is the act or process of converting to the metric system of measurement. All over the world, countries have transitioned from local and traditional Unit of measurement, units of measurement to the metric system. This ...
* Observational error * Replication (statistics) *
Sampling (statistics) In this statistics, quality assurance, and survey methodology, sampling is the selection of a subset or a statistical sample (termed sample for short) of individuals from within a population (statistics), statistical population to estimate char ...
*
Specification (technical standard) 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 ...
* Test management approach *
Verification and validation Verification and validation (also abbreviated as V&V) are independent procedures that are used together for checking that a product, service, or system meets requirements and specification (technical standard), specifications and that it fulf ...


References


General references, books

* Pyzdek, T, "Quality Engineering Handbook", 2003, * Godfrey, A. B., "Juran's Quality Handbook", 1999, * Kimothi, S. K., "The Uncertainty of Measurements: Physical and Chemical Metrology: Impact and Analysis", 2002, {{ISBN, 0-87389-535-5


Related standards

* ASTM E177 Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods * ASTM E691 Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method * ASTM E1488 Standard Guide for Statistical Procedures to Use in Developing and Applying Test Methods * ASTM E2282 Standard Guide for Defining the Test Result of a Test Method * ASTM E2655 - Standard Guide for Reporting Uncertainty of Test Results and Use of the Term Measurement Uncertainty in ASTM Test Methods Metrology Measurement Quality control *