sampling

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Related to cordocentesis: chorionic villus sampling, fetoscopy

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 ?
Enhanced sensitization after cordocentesis in a rhesus-isoimmunized pregnancy.
The role of the laboratory is to support cordocentesis procedures by offering technologies that minimize sample volumes and offer expedited turnaround times (most often, but not limited to, hemoglobin and hematocrit measurements).
Una cordocentesis fue realizada en la 20a semana para la confirmacion de esos resultados; el resultado citogenetico fue normal (46.
En la actualidad estos metodos han sido superados por la aplicacion de las tecnicas de analisis directo o indirecto del acido desoxirribonucleico (ADN) embrionario o fetal, extraido de muestras del producto de la concepcion obtenidas por procedimientos invasivos tales como: biopsia de vellosidades corionicas, amniocentesis y cordocentesis (1, 2, 10, 16).
La discrepancia entre los resultados de los cultivos a corto y largo plazo, como sucedio en este caso, es muy rara y plantea la necesidad de examenes adicionales, en nuestro caso, una cordocentesis.
Mean gestational age in the first cordocentesis was 26.
Se hizo cordocentesis para cariotipo bandeo G a 700 bandas que informo: 47, XX, + 13.
5) Other testing techniques include cordocentesis and foetal tissue sampling.
Cordocentesis para diagnostico fetal citogenetico en Costa Rica.
While level II data still support the use of serial amniocentesis and cordocentesis, today's standard approach is more likely to include ultrasound assessment of late signs such as placental thickness, polyhydramnios, and increasing abdominal circumference, and earlier signs such as fetal liver length and increase in the peak velocity of systolic blood flow in the middle cerebral artery (MCA-PSV), he said.
We had a cordocentesis done to try to establish if our baby had Edwards' Syndrome, but the results of this proved inconclusive.
8, 9] At cordocentesis, a significant correlation has been observed between hypoxemia in fetuses with IUGR and abnormal Middle Cerebral Artery (MCA) Pulsatility Index (PI).