stratified random sample

In order to minimize selection biases, stratified random sampling is often used.

For this study, 300 persons were selected from each of the five regions with stratified random sampling based on gender, age, and income.

This is a stratified random sample of about 2,332 men who registered as unemployed in the autumn of 1978.

The study then consisted of 500 stratified random sampling of e-medicine records.

It uses a stratified random sample technique and an oversample of non-marital births.

In most countries, no upper age limit is imposed and some form of stratified random sampling is used to obtain representative national samples.

A stratified random sample of respondents was then recruited for an extensive overnight protocol including polysomnography at baseline.

Information was obtained from English and Scottish samples selected by stratified random sampling of employment exchange areas with proportionally more children from poorer social groups.

The method used is a stratified random sample of organizations and statistically sound survey methodology and weighting; the study does not use "samples of convenience".

Stratified random sampling designs divide the population into homogeneous strata, and an appropriate number of participants are chosen at random from each strata.

Jerzy Neyman in 1934 showed that stratified random sampling was in general a better method of estimation than purposive (quota) sampling.

A separate stratified random sample of 8016 adults aged 20-79 years was drawn for SHIP-TREND in the same area.

Several types of random samples are simple random samples, systematic samples, stratified random samples, and cluster random samples.

According to the publisher's website, "The SB5 was normed on a stratified random sample of 4,800 individuals that matches the 2000 U.S. Census."

This involves some probability sampling of spatial units, such as random or stratified random sampling of geometrical (often square) or irregular spatial units.

The survey, a stratified random sample of 991 of the nation's 30,000 school districts, was conducted by the association's Educational Research Service, also associated with three other associations of administrators.

Wave 1 of L.A.FANS was fielded between April 2000 and January 2002 in a stratified random sample of 65 census tracts.

For more details on Neyman allocation, see W.G. Cochran, "Stratified Random Sampling," Chapter 5 in Sampling Techniques, 3d ed.

They were the 70.2% of a stratified random sample of women in this age group who accepted an invitation to have ultrasonography of the gall bladder and to answer questions about bowel function, etc.

Patients surveyed represented a stratified random sample of patients in ICUs and outside ICUs for whom blood cultures were either positive or negative, as previously described [ 22 ] .

Using a cross-sectional design, the NYSACS selected a stratified random sample of licensed anglers aged 18-40 years who resided in 16 counties in close proximity to Lakes Erie and Ontario.

While Elmore (1977) laments that sites could have been chosen with a greater degree of scientific rigor (e.g. stratified random sampling), it was obvious that this would have been impossible, for at least two reasons.

Because of the large number of species and stocks analyzed from the bottom trawl surveys and the different bottom types and habitats in the Northeast, the stratified random sampling plan appears to be the most efficient design.

The centre-piece of the study is interviews with a stratified random sample of 120 employees of all levels and departments, designed to test commitment to the firm and motivation to work, alongside opinions about changes actual and in prospect.