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State Oversampling in the National Survey of Children’s Health (NSCH)

When a state would like to better measure specific health outcomes for a particular group, NSCH oversampling is an available option.

Oversampling increases the households sampled in order to increase the number of completed surveys. When there are more data, researchers can examine patterns within specific populations (e.g., looking at specific racial and ethnic groups within the more general population of children and youth with special health care needs).

Types of Oversampling Available

We offer two types of oversampling:

  1. General
    • Increases the overall sample size to support subgroup analyses or more precise annual estimates
  2. Sub-state
    • Increases sample size for certain geographic areas to produce city, county, or regional estimates
    • Increases sample size, and more precise estimates, for racial and ethnic groups who are concentrated in certain geographic areas

Cost Involved

The cost of oversampling depends on the type, size, and number of years to achieve sample size objectives. Since 2020, actual annual costs have ranged from $20,000 to $500,000.

Federal Title V MCH Block Grant allocations can fund oversamples prior to state disbursement. The state Title V Director must make a request through their Project Officer to use this mechanism. Other state and private funds can also be used by establishing a contractual agreement directly with the U.S. Census Bureau.


A state must finalize their plans by July before the data collection year (e.g., July of 2022 for a 2023 oversample). This allows time for routing and signatures.

The U.S. Census Bureau releases data in October following the previous survey year (e.g., 2020 data were released in October 2021).

Accessing Data

Our awardee, The Center for Adolescent Health and Measurement Initiative, provides an interactive web query system to view pre-calculated data tables, charts, and maps for a variety of indicators and characteristics. While anyone can download the public use files for analysis, the U.S. Census Bureau requires an approved project proposal from a Research Data Center to access sub-state geographic identifiers.

Current State Participation

Since 2020, 11 states and 1 metro area have sponsored oversamples.

States Using General Oversampling

The states of Louisiana, Nebraska, Pennsylvania, Wisconsin, and Wyoming used general oversampling. This provides a larger overall sample. In particular, this supports data analysis for Children and Youth with Special Health Care Needs (CYSHCN).

States Using Sub-State Oversampling

There are several types and combinations of sub-state oversampling. States have used the following:

Local area

Colorado targeted oversampling to produce regional estimates. In Georgia, Children’s Healthcare of Atlanta oversampled the Atlanta metropolitan area.


Ohio, Oregon, and Tennessee targeted oversampling for smaller racial and ethnic groups.

Local area + race/ethnicity

California and New York chose to combine these methods. This will increase the sample size in 2022 to produce estimates by county or region and for smaller racial and ethnic groups. Learn more about California’s current effort to use oversampling.

2020 Oversampling Objectives and Completed Interviews

States who oversampled significantly increased their sample size and achieved their objectives.

For example, Wisconsin more than doubled their 2020 sample size. When combined with their 2019 data, this:

  • Yielded a sample size of over 2,000 with more than 500 Children and Youth with Special Health Care Needs (CYSHCN) respondents.
  • Provided more precise estimates of Title V National Performance Measures (NPMs), particularly for CYSHCN.
  • Revealed a statistically significant improvement in the percent of CYSHCN who have received services to prepare for the transition to adult health care (NPM-12) compared to the 2016 baseline (34.0% in 2019-2020 versus 21.1% in 2016).
  • Led to the state developing a CYSHCN surveillance report (to be released in spring 2022), the first of its kind to describe their CYSHCN population in terms of health status, access to care, and disparities.
State Objective Base Interviews Oversample Interviews
Colorado To achieve at least 150 interviews in each of eight regions to produce reliable regional estimates 728 881
Nebraska To increase precision of Title V performance measures through a general oversample of 1,500 addresses 768 315
Oregon To achieve at least 30 interviews for each racial/ethnic group over two years (AI/AN, Asian, Black, Hispanic, NHPI) 767 2,272
Wisconsin To enable CYSHCN subgroup analyses through a general oversample yielding 1,000 extra interviews 709


Information to Help Plan and Design an Oversample

State Oversampling in the National Survey of Children’s Health: Feasibility, Cost, and FAQs (PDF - 887 KB)

Contact Us

Ashley Hirai, Ph.D., Senior Scientist
Office of Epidemiology and Research

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