biased sample

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biased sample

[¦bī·əst ′sam·pəl]
(statistics)
A sample obtained by a procedure that incorporates a systematic error introduced by taking items from a wrong population or by favoring some elements of a population.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

biased sample

a population SAMPLE which is not a true reflection of the parent population (see BIAS 2), i.e. not a REPRESENTATIVE SAMPLE.

When the incidence of a certain occurrence or piece of behaviour in a population is to be investigated, e.g. voting intention, it is often impossible to examine the total population, so a sample of this population is taken. For this sample to produce acceptable data, it must be a true representation of the parent population, so it is essential that it is selected in a way that ensures this. If this is not managed, bias will result and the information collected will not truly reflect the population being studied. Thus, to select a sample by questioning people in the street will bias it against people who do not walk, do not go shopping, are at work or school all day Postal QUESTIONNAIRES attempt to overcome this type of bias, but are likely to be biased against those who do not bother to fill in questionnaires and re turn them, and against the illiterate. To keep bias to a minimum, if random sampling is not possible, it is necessary to select the sample carefully by matching all relevant parameters of the population, e.g. age, class, residence, etc, and to ensure as high a response rate as possible, probably by personal INTERVIEWS.

Collins Dictionary of Sociology, 3rd ed. © HarperCollins Publishers 2000
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References in periodicals archive ?
Diebolt, "Describing the geometry of 3D fracture systems by correcting for linear sampling bias," Mathematical Geology, vol.
Without abandoning respondent-driven sampling altogether, alternative considerations within its methodology could diminish the effects of sampling bias. The study used staff-selected seeds to participate and recruit additional participants.
However, several dissertations (50%) used the non-probability sampling, either quota or purposive, which is less appropriate for a quantitative study for such does not control sampling bias and limits representativeness.
Among numerous other flaws, these data suffer from serious sampling bias. First, a sick animal wouldn't be slaughtered for meat.
We determined the relative strength of influenza migratory connections between Vietnam and the rest of the world, and we interpreted these results in the context of a sampling bias that seems to affect all sequence-based studies aiming for phylogeographic interpretations.
In contrast, achieving a diagnosis of cystic lesions of the parotid by FNAB can be challenging and even difficult because of sampling bias and the limitations on interpretation.
Over-sampling in locations that are easily accessible often leads to sampling bias, which affects model performance.
Lovich and Gibbons (1990) list several factors that may influence sex ratios in wild terrapin populations: environmental sex determination (ESD), age at maturity, sampling bias, seasonal variation, and differential mortality between the sexes.
Marin County is home to WildCare, an animal rescue and rehabilitation center that routinely submits animal remains for diagnostic testing, which might result in a sampling bias.
Sampling bias was kept into account when defining the inclusion and exclusion criteria for the sample.
There have been major developments here too, with a significant gain being the greater efficiency of the latest wet dispersion accessories that cut sample preparation time and eliminate sampling bias. Arguably, though, it is the developments in dry dispersion that are even more beneficial since they extend the range of materials for which dry measurement is viable.