sampling

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sampling

the selection of part of a total population of consumers or products whose behaviour or performance can be analysed, in order to make inferences about the behaviour or performance of the total population, without the difficulty and expense of undertaking a complete census of the whole population.

Samples may be chosen randomly, with every consumer or product in the population having an equal chance of being included. Random samples are most commonly used by firms in QUALITY CONTROL where they are used as a basis for selecting products, components or materials for quality testing.

Alternatively, samples may be chosen by dividing up the total population into a number of distinct sub-groups or strata, then selecting a proportionate number of consumers or products from each sub-group since this is quicker and cheaper than random sampling. In MARKETING RESEARCH and opinion polling, quota sampling is usually employed where interviewers select the particular consumers to be interviewed, choosing the numbers of these consumers in proportion to their occurrence in the total population.

Samples may be:

  1. cross-sectional, where sample observations are collected at a particular point in time, for example data on company sales and the incomes of consumers in the current year, embracing a wide range of different income groups, as a basis for investigating the relationship between sales and income;
  2. longitudinal, where sample observations are collected over a number of time periods, for example data on changes in company sales over a number of years and changes in consumer incomes over the same time periods, as a basis for investigating the relationship between sales and income. See STATISTICAL INFERENCES, QUESTIONNAIRE.
Collins Dictionary of Business, 3rd ed. © 2002, 2005 C Pass, B Lowes, A Pendleton, L Chadwick, D O’Reilly and M Afferson
References in periodicals archive ?
[1989]: 'Random Sampling and Methods of Estimation', Proceedings of the Aristotelian Society, 89, pp.
Keeping track of the interval of patients to be selected with systematic random sampling requires additional time and effort by the data collection team.
Firstly, a ratio estimator for population variance using auxiliary information in simple random sampling was proposed (Isaki, 1983):
Even within the stratified random sampling framework, there is some technical variation across states.
For the present study, six government and nine private hospitals were selected using simple random sampling techniques.
Undergraduate students of BS Paramedical Sciences were enrolled through simple random sampling. Assuming the anticipated proportion to be 0.5 and absolute precision required as 0.07 and a=0.05, sample size of 196 was calculated as:
"There are lots of things that may lead to contamination and they arise at different points within the supply chain," he told The Daily Star, adding that random sampling was not the way to build a full picture.
A few days earlier, on March 8-11, SWS had done face-to-face interviews of 1,200 validated voters, drawn nationwide by means of standard SWS random sampling procedures.
Sami bin Salim al- Sahib, Acting Director General of Standards and Metrology at Ministry of Commerce and Industry said in a statement that the random sampling comes as a precautionary measure to ensure that the Omani markets contains no such harmful products, despite the fact that the Sultanate is not on the list of the 55 countries which recalled the products of Mars Chocolate Company because of the possibility of the existence ofplastic bits in it.
Sami bin Salim Al Sahib, acting director general of Standards and Metrology at the Ministry of Commerce and Industry said in a statement that the random sampling was done as a precautionary measure to ensure that Omani markets contain no such harmful products, despite the fact that the Sultanate is not on the list of the 55 countries, which recalled the products of Mars Chocolate Company because of the possibility of the existence of plastic bits in it.
In the present article, we have proposed a class of ratio estimators for the estimation of finite population mean using simple random sampling scheme when there is maximum and minimum values on both the study and the aux iliary variables and their properties are considered up to the first order of approximation.
From the total number (35) of collected rat placentas, it is not distinguishable how many inhered to each group and it is difficult to understand how they managed the random sampling. Although random sampling may be achieved in different ways (and each time it is possible to make an unbiased sampling and research), the results may vary in efficiency depending on the heterogeneity of the specimen itself [2].