sample (redirected from stratified random sample)

sample

Etymology: L, exemplum

(in research) a group or part of the whole that can be used to demonstrate characteristics of the whole. Kinds of samples include cluster, convenience, random, and stratified.

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sample 

1. a representative part taken to typify the whole.

2. a subset of a population that is selected for inclusion in a research study.

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sample,

n a selected part of a population that is taken to be representative of the whole population.

sample, random,

n a sample drawn by chance; a sample drawn in such a way that every item in the population has an equal and independent chance of being included in the sample.

sample, stratified,

n a sample derived by dividing the population into a number of nonoverlapping classes or categories from which cases are selected at random, the number of cases selected from each category being proportional to the number therein.

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sample

1. a specimen of fluid, blood or tissue collected for analysis on the assumption that it represents the composition of the whole.

2. for statistical purposes a small collection of individual units taken from the population which is under investigation on the assumption that they represent the characteristics of the entire population.

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EPSEM sample

acronym for 'equal opportunity of selection method'.

grab sample

sample of greasy wool taken at random by a special machine from each bale on the sale floor. Buyers price the bale on the basis of the appearance of the grab sample and the objective measurements.

multi-stage random sample

with very large populations it may be desirable to arrange the data into groups on one criterion, e.g. address by area of postcode, and to select randomly from within this group, then select from within this sample to obtain randomly a representative number of specimens, such as dogs of each age group.

random sample

the selection from a population of the units which are to constitute the sample of that population is made in such a way that each unit of the population has an equal chance of being selected. Called also simple random sample.

simple random sample

see random sample (above).

stratified random sample

the data is arranged into subsets or strata based on the possession of certain characteristics which are common to the members of the subset. The selection of units to comprise the sample of the parent population is arranged so that the proportional representation of each subset in the final sample fits a prearranged schedule.

volunteer sample

sample donated by interested parties; a biased sample because it does not represent all sections of the population. Called also self-selection.

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sampling 

The selection of a group of subjects from a population. This is usually done for the purpose of experimentation. The part of the population selected is called the sample: it is usually considered to be representative of a given population. A good sample must be random, i.e. every possible member of that population has an equal chance of being selected. Otherwise, it is said to be biased. Sampling can extend either across geographical areas (spatial sampling) or over a period of time (temporal sampling).