quota sample


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Related to quota sample: stratified sample, cluster sample, Snowball sample

quota sample

a population SAMPLE selected by quotas from each defined portion of the population. The method of quota sampling does not fulfil the normal requirements of RANDOM SAMPLING. It involves breaking down the parent populations into strata (see STRATIFIED SAMPLING) according to relevant features (e.g. sex, age, social class, place of residence), and calculating how many individuals to include in each of these categories to reflect the parent population structure. At this stage randomness can be achieved, but once the size of each of these cells (i.e. the number of people of a certain sex, age and class living within a certain location) is decided, no attempt at randomness is made. Instead, the interviewers are instructed to achieve appropriate selections (quotas) to fulfil the requirements within each cell.

This lack of randomness in the selection of respondents means that though the interviewers achieve the correct proportion of the sexes, of age groups, of social class, etc., there is likely to be BIAS introduced on other VARIABLES since each member of the parent population has not had an equal chance of being chosen as a member of the sample (the criterion of randomness). MARKET RESEARCH and opinion polls commonly use this method for its cheapness and speed, but selecting a sample from individuals walking in town centres during daylight hours obviously risks biasing the sample on other variables than those specifically selected for.

References in periodicals archive ?
A quota sample consisting of 150 face-to-face interviews representative of the 1990 census data for the Greater Tampa Bay Area was used for this study.
Research Methodology The research was conducted by Ipsos MORI using an online survey among a representative quota sample of 1,000 adults aged 16-75 in GB between 28 November and 5 December 2014.
She expanded coverage of the prices of services in the Producer Price Index and instituted improvements in the Current Employment Statistics program, including the substitution of a probability sample for the quota sample.
Mori interviewed a nationally representative quota sample of 866 adults aged 15-plus (excluding health professionals) from 188 sampling points across Britain.