Dating statistics united states
In one state and one large urban school district, all students in sampled schools were eligible to participate.Survey procedures for the national, state, and large urban school district surveys were designed to protect students’ privacy by allowing for anonymous and voluntary participation.This questionnaire was used as the starting point for the state and large urban school district questionnaires.States and large urban school districts could add and/or delete questions from the standard questionnaire.
Before the 2013 national YRBS, three strategies were used to oversample black and Hispanic students: 1) larger sampling rates were used to select PSUs that were in high-black and high-Hispanic strata; 2) a modified measure of size was used to increase the probability of sampling schools with a disproportionately high minority enrollment; and 3) two classes per grade, rather than one, were sampled in schools with a high minority enrollment.
Because of increases in the proportions of black and Hispanic students in the population, only selection of two classes per grade was needed in 20 to balance the precision needed for subgroup estimates with minimum variance for overall estimates.
In 2015, a two-stage cluster sample design was used to produce a representative sample of public school students in grades 9–12 in one state (South Dakota).
Among those with weighted data for 2015, three state and one large urban school district surveys were conducted during fall 2014; the national survey, 29 state, and 16 large urban school district surveys were conducted during spring 2015; and five state and two large urban school district surveys were conducted during fall 2015. A three-stage cluster sample design produced a nationally representative sample of students in grades 9–12 who attend public and private schools.
The first-stage sampling frame consisted of 1,259 primary sampling units (PSUs), consisting of counties, subareas of large counties, or groups of smaller, adjacent counties.