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random samplea SAMPLE from a parent population selected by ensuring that each member of that population has an equal chance of being selected. When this is observed the sample should have the same profile of features as the parent population, i.e. it should be a valid representation of it. Data collected by random sampling (assuming the sample is large enough) should reflect the parent population, but methods which are not random (e.g. QUOTA SAMPLING) cannot be relied on to do so. However, it is recognized that samples are not entirely accurate, thus account must be taken of SAMPLING ERROR.
The methods used to achieve random selection may be based on random number tables or, more usually in social surveys, on systematic sampling, i.e. selecting individuals, households, etc. according to their position on a list, such as the ELECTORAL REGISTER, when a sample of every name at a fixed interval, say the tenth on the list, is made. See also PROBABILITY.