Stratified Random Samples
. When data is sampled as in one-phase or two-phase case-control studies, there are groups within which the selection probabilities are equal.
Specialty choice probabilities obtained through standard scoring for the 16 medical specialties were generated for each member of the stratified random sample
by using beta weights (which were derived from multino-mial logistic regression analysis) with 30 out of 150 MSPI-R items.
Data Source: The data are from a stratified random sample
of more than 5,000 hemodialysis patients in the United States who were treated at about 140 dialysis facilities between August 2010 and April 2012, corroborated by Medicare claims data.
The researchers solicited the views of a stratified random sample
of 4,508 Florida residents, with smaller random samples from California (500), Texas (502) and New York (502).
The primary data sources for the study consisted of all ACT-tested 2003 high school graduates (for enrollment) and a stratified random sample
of 24,850 of these high school graduates who immediately enrolled in college in fall 2003 (for retention and degree completion).
As shown in Table 1, a stratified random sample
of blue newspapers was used to account for the fact that the five most blue states contained 56 newspapers while the 5 most red states contained only 19 newspapers.
On the other hand, the McREL data is not a stratified random sample
of the US teacher population (the way the PBS data is).
MORTECH 2010, based on a stratified random sample
of mortgage lenders, found that:
Of the 121 students participating in the study, Certo interviewed a stratified random sample
of 24, after they participated in such small-group literature discussions for four months.
(6) These estimates differ from Savage and Hodges (2006) because their analysis was based on a stratified random sample
. TABLE 2.
METHODS: A stratified random sample
of 467 residents of East Boston, Massachusetts, 65 years of age or older, were given structured neurologic examinations.
Using the 2006 Canadian Census, a stratified random sample
of 6,421 women over age 14 with singleton live births in the previous three months were identified and interviewed about socio-economic and demographic information; reproductive history; folic acid use; prenatal care; smoking, alcohol and street drug use; stress and support; physical and sexual abuse; information received about pregnancy, birth and post-partum issues; interventions during pregnancy, labour and delivery; post-partum health and care; postpartum depression; and infant feeding.