standard(redirected from standard error of the mean)
Also found in: Dictionary, Thesaurus, Medical, Legal.
An accepted reference sample which is used for establishing a unit for the measurement of physical quantities. A physical quantity is specified by a numerical factor and a unit; for example, a mass might be expressed as 8 g, a length as 6 cm, and a time interval as 2 min. Here the gram is a mass unit defined in terms of the international kilogram, which serves as the primary standard of mass. The centimeter is defined in terms of the international meter, which is the primary standard of length and is defined as the length of path traveled by light in a vacuum during a time interval of 1/299,792,458 of a second. In similar fashion, the minute is a time interval defined as 60 s, where the second is the international standard of time and is defined as the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine energy levels of the ground state of the cesium-133 atom.
The National Institute of Standards and Technology in the United States and comparable laboratories in other countries are responsible for maintaining accurate secondary standards for various physical quantities. See Electrical units and standards, Light, Metric system, Physical measurement, Time
in the broad sense of the word, a sample or model used as an original for purposes of comparison with other objects; a normative technical document related to standardization that establishes a set of norms, rules, and requirements for the object being standardized and is approved by a recognized authority. Standards may be formulated for materials and technical objects (products, models, samples), as well as for norms, rules, general technical requirements, and requirements relating to organization and methodology. Standards are used in all spheres of human activity, including science, engineering, industrial and agricultural production, construction, public health, and transportation.
In the USSR, standards are classified according to the field in which they are used and the extent to which they have been adopted. State standards (GOST’s) are approved by the State Committee on Standards of the USSR (with the exception of standards ratified by the Council of Ministers of the USSR, the State Committee for Construction of the USSR, and the Ministry of Public Health of the USSR) and are applied throughout the USSR. Sectorial standards (OST’s) are approved by a single ministry and are compulsory for all enterprises in that particular sector. Standards of the Union republics (RST’s) are approved by a republic’s Council of Ministers and are compulsory for all enterprises located in the republic regardless of the departments to which the enterprises are subordinate. Enterprise and association standards (STP’s) are compulsory only for the enterprises adopting them. Standards of the Council for Mutual Economic Assistance (COMECON standards), which reflect the activity of COMECON standardization bodies, have been introduced in the USSR. Adherence to COMECON standards is compulsory for all enterprises, organizations, and institutions under Union, republic, or local jurisdiction in all branches of the national economy. Alongside standards, the USSR uses technical specifications for specific grades, brands, and types of output.
Standards are also classified according to purpose. One category includes general technical rules and norms and rules and norms pertaining to organization and methodology; a second group encompasses general requirements, indexes, and norms for product quality. Operating features, technical characteristics, and methods for inspecting uniform items that are used interin-dustrially constitute a third group. Another group includes safety norms and procedures and terms and designations. Fundamental units of physical quantities constitute a separate group, as do state standards for units of physical quantities and testing schemes. Methods and means of testing measuring equipment are in a separate group, as are requirements for standard samples with regard to the properties and composition of the substances and materials. Systems of documentation, for example, those pertaining to design and technology, form yet another group. A separate category is also reserved for systems of classifying and codifying technical and economic information and systems of organizing production and effecting a scientific organization of labor. The final category of standards covers the most important types of output.
Production standards include those governing technical specifications, general technical requirements, parameters, types, design, grades, assortments, rules for acceptance, monitoring methods, grading rules for marking, packaging, transportation, storage maintenance and technological processes. All standards are systematically reviewed and updated to conform with the latest advances of science, technology, and production. In the USSR, standards are mandatory in the fields in which they have been adopted. Procedures for the formulation and adoption of standards are set forth in GOST 1.2–68. All official information concerning USSR state standards is published in the monthly Informatsionnyi ukazatel’ gosudarstvennykh standartov SSSR (Information Directory of State Standards of the USSR) and in the annual Ukazatel’ gosudarstvennykh standartov SSSR (Directory of State Standards of the USSR).
V. V. BOITSOV
(1) The banner carried by Russian cavalry units from 1731 to 1917 and by various foreign armies from the 18th to the 20th century. It consisted of a square cloth smaller than the regular banner. The staff was fitted to the stirrup and grasped by the horseman by means of a looped strap.
(2) The personal flag of a head of state, such as a monarch or president, used in several countries in the 19th and 20th centuries, including Russia. It served to mark the position of the head of state, for example, in the palace or on board a ship.
(in Russian, etalon), a measuring device (sredstvo izmerenii) or a set of measuring devices that reproduces and preserves the adopted value of a unit of a physical quantity or that transfers the size of such a unit to other measuring devices. Without standards, it is impossible to compare the results of measurements made with different instruments, in different places, or at different times.
Because standards must be extremely accurate, the establishment, maintenance, and use of standards requires special research and development work, which is carried out by national metrology laboratories. For the international standardization of units, international standards—in particular, the standards of the member states of the Council for Mutual Economic Assistance (COMECON)—are established. In addition, national standards are established within an individual country.
In the USSR, standards are classified as primary, special, and secondary. A primary standard reproduces a given unit to the highest level of accuracy attainable in the country. Special standards are used to reproduce units under special conditions—for example, at high or ultralow temperatures or pressures—where primary standards cannot be used. Primary and special standards are accepted as national standards (gosudarstvennye etalony), that is, as the standards at the top of all-Union calibration hierarchies for the corresponding types of measurements (seeCALIBRATION OF MEASURING DEVICES). Secondary standards are used to transfer the sizes of units to base standards (obraztsovye sredstva izmerenii) and to the most accurate working standards (rabochie sredstva izmerenii).
Depending on their metrological purpose, secondary standards are subdivided into transfer standards, reserve standards, comparison standards, and working standards (rabochie etalony). Transfer standards are substituted for national standards when the sizes of units are transferred to working standards. Reserve standards are used to check the constancy of national standards and the invariability of units reproduced by national standards. Comparison standards are used to intercompare the standards maintained at different metrology laboratories when the transportation of the standards to be intercompared is impossible or undesirable. Working standards are used for routine work in the transfer of the sizes of units to base standards.
All the standards used in the USSR constitute the basis for metrological work in the national economy. This basis includes standards for the base units of the International System of Units (SI), a number of primary standards for SI derived units, and special standards (see).
The SI base units include the meter, kilogram, second, ampere, kelvin (formerly “degree Kelvin”), and candela. The standard for the meter is a standard interferometer and a krypton lamp; the standard meter is equal to a certain number of wavelengths of the orange line in the spectrum of krypton-86. The kilogram mass standard consists of a platinum-iridium weight and standard scales. The time and frequency standard, which is used to establish the second and the hertz, is a set of equipment for generating electromagnetic oscillations of a strictly constant and known frequency and for transmitting time and frequency radio signals. The standard for the ampere consists of a current balance and equipment both for controlling the balance and for the absolute determination of the electromotive force of a reference voltage. The standard for the kelvin comprises primary fixed temperature points and interpolation equipment (seeINTERNATIONAL PRACTICAL TEMPERATURE SCALE). The standard for the candela consists of a complete, or blackbody, radiator at the freezing point of platinum and devices for comparing standard photometric lamps with the complete radiator (seePHOTOMETRIC STANDARD).
State standards (gosudarstvennye standarty) are published for national standards and all-Union calibration hierarchies. National standards must be recorded in a special catalog.
In the USSR, standards are kept at specialized metrology institutes of the State Committee for Standards of the Council of Ministers of the USSR (Gosstandart SSSR), mainly at the D. I. Mendeleev All-Union Research Institute of Metrology in Leningrad. Some working standards have been transferred to institutes that are affiliated with other ministries or agencies and that carry out metrological work of an especially high accuracy.
In other countries, the classification of standards differs somewhat from that presented above since the standards used also include base standards (obraztsovyesredstva izmerenii). Every metrological agency has its own reference standards and working standards. National calibration hierarchies are not organized in all countries. The most important metrology laboratories that establish and maintain national standards include the National Bureau of Standards in the USA, the National Physical Laboratory in Great Britain, the National Research Council of Canada, the Federal Institute of Physics and Technology in the Federal Republic of Germany, and the National Standards Laboratory in Australia.
International standards established in the framework of the Metric Treaty are kept at the International Bureau of Weights and Measures in Sevres, near Paris. International standards established in the framework of COMECON are kept at authorized national metrology laboratories in the member states of COMECON.
REFERENCESBurdun, G. D., and B. N. Markov. Osnovy metrologii. Moscow, 1972.
Metrologicheskaia sluzhba SSSR. Moscow, 1968.
Gosudarstvennye etalony SSSR: Spravochnik. Moscow, 1976.
K. P. SHIROKOV
Andrew Tanenbaum, in his Computer Networks book, once said, "The nice thing about standards is that there are so many of them to choose from", a reference to the fact that competing standards become a source of confusion, division, obsolescence, and duplication of effort instead of an enhancement to the usefulness of products.
Some bodies concerned in one way or another with computing standards are IAB (RFC and STD), ISO, ANSI, DoD, ECMA, IEEE, IETF, OSF, W3C.