# random sample

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Related to random sample: stratified random sample

## ran·dom sam·'ple

a selection on the basis of chance of individuals or items in a population for research; selection is made in such a way that all members presumably have the same chance of being selected.

## random sample

A population sample selected by a randomisation method designed to ensure that each subject or patient in a target group has an equal chance of being selected for the treatment arm of the study.## random sample

Statistics A population sample derived by selecting individuals, such that each has the same probability of selection; a group of subjects selected in such a way that each member of the population from which the sample is derived has an equal or known chance–probability–of being chosen for the sample. See Sampling.## ran·dom sam·ple

(randŏm sampĕl)Selection on basis of chance of individuals or items in a population for research.

## random

unplanned, without direction or purpose.

**random assignment**

see randomization.

**random mating**

where each member of the population has an equal opportunity of mating with every member of the opposite sex.

**random numbers**

a list of numbers obtained by a standard randomization procedure; used commonly to select individual animals from a pack.

**random sample**

see random sample.

**random sampling**

a procedure for selecting units from a group in such a way that each unit has an equal chance of being selected in the sample.

**random selection**

selection in such a way as to produce a random sample.

**random variable**

a group or quantity that takes various values, each with varying probabilities.

## 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.

**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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