sampling

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Related to purposive sampling: Snowball sampling

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.
References in periodicals archive ?
tested Province Random sampling Purposive sampling Drenthe 0/99 NA Flevoland 0/37 NA Friesland 0/62 0/1 Gelderland 2/97 0/12 Groningen 0/32 NA Limburg 3/46 0/1 North Brabant 3/101 0/5 North Holland ([section]) 0/0 NA Overijssel 9/87 5/18 South Holland 0/7 0/10 Utrecht 0/16 0/1 Zealand ([section]) 0/8 NA Total 17/592 5/48 Identification Province no.
Also, most of the reviewed studies employed purposive sampling as the sampling technique in their research.
The research applied various purposive sampling techniques - stratified purposive, snowball and convenience sampling techniques - to select the sample from heterogeneous population in order to record the diversity of opinions.
Patients diagnosed as RA according to American College of Rheumatology (ACR) 1987 criteria1 with age above 16 years and both gender were enrolled through purposive sampling from Division of Rheumatology, Fatima Memorial Hospital from Sep 2014 to Feb, 2015.
The sample comprised of 45 diagnosed patients of epilepsy and 40 non epileptic by using the purposive sampling. The epileptic patients were taken from S.S.
250 grandparents are selected through multi-purpose sampling, which can be stratified into two parts: purposive sampling to identify family with exceptional child/ children with the support of Parents Teacher Association (PTA); snowball sampling: to select the respondents from Karachi, Pakistan.
Cross Sectional 67,857 Multiple locations, multiple sites Purposive sampling Ganapati et al.
The random and purposive sampling techniques of data collection were used.
177 cirrhotic patients were included in this study via non-probability, purposive sampling. Data was analyzed using SPSS Version 19.
While the size, according to Polit and Beck (2012), may be acceptable because of the purposive sampling, it is not clear about its influence on data saturation.
Purposive sampling was used to select mothers who had delivered 6 months before the study, identified through VHT registers, as they were expected to readily recall experiences with VHTs.