“sampling”的概念、定义、翻译、参考文献-科学参考

sampling

Physics

The selection of small groups of entities to represent a large number of entities in statistics. In random sampling each individual of a population has an equal chance of being selected as part of the sample. In stratified random sampling, the population is divided into strata, each of which is randomly sampled and the samples from the different strata are pooled. In systematic sampling, individuals are chosen at fixed intervals; for example, every hundredth article on a production line. In sampling with replacement, each individual chosen is replaced before the next selection is made.

Computer

1. (time quantization) A process by which the value of an analogue, or continuous, signal is ‘examined’ at discrete fixed intervals of time. The resulting sampled value will normally be held constant until the next sampling instant, and may be converted into a digital form using an A/D converter for subsequent processing by a computer.
The rate at which a given analogue signal is sampled must be a certain minimum value, dependent upon the bandwidth of the analogue signal; this ensures that none of the information in the analogue signal is lost. The sampling rate may also affect the stability of an analogue system if the system is to be controlled by a computer. See also Nyquist’s criterion.
2. The act of selecting items for study in such a way that the measurements made on the items in the sample will provide information about similar items not in the sample. Items can be people, machines, periods of time, fields of corn, games of chance, or whatever is being studied. Sample size is the number of items included in the sample. If the variance of the measurement (see measures of variation) is approximately known, the variance of its mean in a sample is the population variance divided by the sample size. This formula can then be used to indicate an appropriate sample size.
A population is a complete set of items about which information is required. It must be defined before selecting the sample or results may be ill-defined. The sample is the basis for inference about probability distributions of measurements on the population. Problems of sampling include avoidance of bias and selection of enough samples to ensure adequate precision.
Random sampling is the process that results in each item having the same probability of inclusion in the sample. Items may be selected with the aid of tables of random numbers or with mechanical devices such as cards or coins.
Systematic sampling selects items in some regular manner. It is valid when the order in which items are encountered is irrelevant to the question under study, but can be an unintentional source of bias.

Electronics and Electrical Engineering

1. A technique in which only some portions of an electrical signal are measured and are used to produce a set of discrete values that is representative of the information contained in the whole. In order that the output values represent the input signal without significant loss of information, the rate of sampling – the sampling frequency – of a periodic quantity must be at least twice the frequency of the highest component in the signal. The minimum sampling frequency is known as the Nyquist rate.
A sampling circuit is used to produce a set of discrete values representative of the instantaneous values of the input signal. The output may be in the form of a set of instantaneous values (instantaneous sampling) or in a coded form. The technique is widely used in analogue-to-digital converters, digital voltmeters, multiplex operation, pulse modulation, etc.
2. A technique in which intermittent measurements of an electrical signal are made. The technique is used in feedback control systems where the controlled variable is sampled intermittently and a correction applied if necessary as a result of the instantaneous value (the sample intelligence). The technique is also used in radio-navigation systems when information from the navigation signal is extracted only when the sampling gate is activated by a selector pulse and therefore interrogates the signal and produces a corresponding output pulse or waveform.
3. A system of quality control of mass-produced electronic components, circuits, devices, or other equipment. Random samples of the manufactured items are removed from the manufacturing point and tested exhaustively. The sampling process is usually carried out for each processing stage during manufacture.

Biology

In statistics and experimental design, the selection of a small group of entities to represent a larger population of entities. In random sampling, a chance process is used so that each individual of a population has an equal chance of being selected as part of the sample. In stratified sampling, the population is divided into subgroups or strata (e.g. male and female), and the number of individuals chosen from each corresponds to the relative size of that group within the population. In systematic sampling, individuals are chosen at fixed intervals; for example, every tenth animal in a population. In sampling with replacement, each individual chosen is returned to the general pool before the next selection is made (with the effect that some items may be selected more than once).

单词	sampling
释义	sampling Physics The selection of small groups of entities to represent a large number of entities in statistics. In random sampling each individual of a population has an equal chance of being selected as part of the sample. In stratified random sampling, the population is divided into strata, each of which is randomly sampled and the samples from the different strata are pooled. In systematic sampling, individuals are chosen at fixed intervals; for example, every hundredth article on a production line. In sampling with replacement, each individual chosen is replaced before the next selection is made. Computer 1. (time quantization) A process by which the value of an analogue, or continuous, signal is ‘examined’ at discrete fixed intervals of time. The resulting sampled value will normally be held constant until the next sampling instant, and may be converted into a digital form using an A/D converter for subsequent processing by a computer. The rate at which a given analogue signal is sampled must be a certain minimum value, dependent upon the bandwidth of the analogue signal; this ensures that none of the information in the analogue signal is lost. The sampling rate may also affect the stability of an analogue system if the system is to be controlled by a computer. See also Nyquist’s criterion. 2. The act of selecting items for study in such a way that the measurements made on the items in the sample will provide information about similar items not in the sample. Items can be people, machines, periods of time, fields of corn, games of chance, or whatever is being studied. Sample size is the number of items included in the sample. If the variance of the measurement (see measures of variation) is approximately known, the variance of its mean in a sample is the population variance divided by the sample size. This formula can then be used to indicate an appropriate sample size. A population is a complete set of items about which information is required. It must be defined before selecting the sample or results may be ill-defined. The sample is the basis for inference about probability distributions of measurements on the population. Problems of sampling include avoidance of bias and selection of enough samples to ensure adequate precision. Random sampling is the process that results in each item having the same probability of inclusion in the sample. Items may be selected with the aid of tables of random numbers or with mechanical devices such as cards or coins. Systematic sampling selects items in some regular manner. It is valid when the order in which items are encountered is irrelevant to the question under study, but can be an unintentional source of bias. Electronics and Electrical Engineering 1. A technique in which only some portions of an electrical signal are measured and are used to produce a set of discrete values that is representative of the information contained in the whole. In order that the output values represent the input signal without significant loss of information, the rate of sampling – the sampling frequency – of a periodic quantity must be at least twice the frequency of the highest component in the signal. The minimum sampling frequency is known as the Nyquist rate. A sampling circuit is used to produce a set of discrete values representative of the instantaneous values of the input signal. The output may be in the form of a set of instantaneous values (instantaneous sampling) or in a coded form. The technique is widely used in analogue-to-digital converters, digital voltmeters, multiplex operation, pulse modulation, etc. 2. A technique in which intermittent measurements of an electrical signal are made. The technique is used in feedback control systems where the controlled variable is sampled intermittently and a correction applied if necessary as a result of the instantaneous value (the sample intelligence). The technique is also used in radio-navigation systems when information from the navigation signal is extracted only when the sampling gate is activated by a selector pulse and therefore interrogates the signal and produces a corresponding output pulse or waveform. 3. A system of quality control of mass-produced electronic components, circuits, devices, or other equipment. Random samples of the manufactured items are removed from the manufacturing point and tested exhaustively. The sampling process is usually carried out for each processing stage during manufacture. Biology In statistics and experimental design, the selection of a small group of entities to represent a larger population of entities. In random sampling, a chance process is used so that each individual of a population has an equal chance of being selected as part of the sample. In stratified sampling, the population is divided into subgroups or strata (e.g. male and female), and the number of individuals chosen from each corresponds to the relative size of that group within the population. In systematic sampling, individuals are chosen at fixed intervals; for example, every tenth animal in a population. In sampling with replacement, each individual chosen is returned to the general pool before the next selection is made (with the effect that some items may be selected more than once).
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