Disability and Health Data System (DHDS) Frequently Asked Questions

Data source and methodology

Where does Disability and Health Data System (DHDS) get its data?

Data displayed in DHDS come from the Behavioral Risk Factor Surveillance System (BRFSS). The BRFSS is a state-based telephone interview in which an interviewer asks questions on a variety of health risks and behaviors, chronic conditions, and demographics. More information on the BRFSS.

Why are the percentages age-adjusted?

Disability often is associated with older age. Age-adjustment is a statistical technique that minimizes the effects of age and allows for meaningful comparisons across populations with different age distributions. For example, if state "A" had a very young population, and state "B" had an older population, you would expect a higher percentage of people with disabilities in state "B" because of the older age of the population. By age-adjusting to a standard age distribution, the percentage of people with disabilities in state "A" and state "B" can be compared directly.

How often will data be added?

DHDS strives to display the latest data available. We aim to add BRFSS data within 1 year following the annual public release.

The United States & Territories estimates are different than estimates I have seen elsewhere. Why?

National estimates from other surveys might appear slightly different due to survey methodology, survey population, definitions of the indicators, and analytical techniques. The estimates presented here for United States & Territories are meant to be used more as benchmarks with which to compare your state or area, not as comparisons with other national surveys. In DHDS, United States & Territories estimates are calculated from the aggregate of the state and territory data.

Why do the prevalence estimates of the disability types not add up to the prevalence estimate of any disability?

The cognitive, hearing, mobility, vision, self-care, and independent living disability types are not mutually exclusive, meaning that people can report more than one type of disability. A person is categorized as having any disability if he or she has one or more disability types. Therefore, while someone may have two or more disability types, they are only counted once in the prevalence calculation for any disability.

What is a 95% confidence interval?

A 95% confidence interval (CI) is a range of values surrounding the estimate (percent) in which the actual population measure lies with 95% confidence. This means that if a population were surveyed 100 times, and a 95% CI calculated for each of the 100 surveys, then the actual measure for the entire population is expected to be contained within the calculated CIs for 95 of the 100 surveys. A 95% CI represents statistical reliability. Specifically, a wide interval indicates the percentage estimate is less reliable, and a narrow interval indicates the percentage estimate is more reliable. Asymmetric confidence intervals are reported in DHDS and are shown as (Low Confidence Limit – High Confidence Limit).

Data availability

What kinds of data are included in DHDS?

DHDS contains disability status and types data, which are available for a number of demographic and health topic indicators. Indicators are grouped into the following categories:

• Disability Estimates
• Demographics
• Health Risks & Behaviors
• Prevention & Screenings
• Barriers & Costs of Health Care
• General Health Conditions
• Chronic Conditions
• Mental & Emotional Health

How do I find the definition and other information for an indicator?

You can find indicator definitions in the DHDS data guide. This guide provides information about how each indicator is defined and analyzed.

Which geographic levels are available for the data?

Data are available at the state, U.S. Department of Health and Human Services (HHS) region, and national levels. Data for all geographic levels are available by location and by indicator. The exception is HHS region data, which is not available in the "by indicator" map view.

Why are there no data for my state or territory?

Data for a state or territory might have been suppressed due to either a small sample size or unreliable estimates. Footnoted locations in the map view, missing bars in the chart view, and missing locations or footnoted cells in the table view indicate data are suppressed or not reported.

About using DHDS

How do I download DHDS data?

To download the DHDS dataset, click the DHDS Data Portal link from the homepage. From there, you will be able to download the full DHDS dataset or create your own filtered dataset for download. To download a subset of DHDS data based on a data panel that you have customized in the Explore by Location or Explore by Indicator sections of DHDS, or a comparison report you have customized, click the "Export CSV File (.csv)" links available in those sections.

How do I save maps, charts, tables, or reports from DHDS?

In the Explore by Location section of DHDS, you can save the page by clicking the "Save as PDF" link at the top of the page, or you can save an individual data panel by clicking the "Save as PDF" link in that particular panel.

In the Explore by Indicator section of DHDS, you can save the page by clicking the "Save as PDF" link at the top of the page.

You can also capture a picture of your desktop by holding down Ctrl and Print Screen, or by using a screen-grabbing software.

I do not know the U.S. Department of Health and Human Services (HHS) region to which my state belongs. How do I find out?

Data in DHDS were aggregated to produce estimates for the ten HHS regions.

Learn more about these regions and find out to which region your state belongs.

What is CSV, or comma-separated values?

CSV is a type of simple file format commonly used to transfer tabular data into a spreadsheet or database. This format is particularly useful for users without access to Excel.

General

I have other questions. Whom should I ask?

You can email CDC-INFO and we will be happy to answer any questions.

How do I cite DHDS?

To cite data or information obtained from DHDS, please use the following text: Centers for Disease Control and Prevention, National Center on Birth Defects and Developmental Disabilities, Division of Human Development and Disability. Disability and Health Data System (DHDS) Data [online]. [accessed month day, year]. URL: https://dhds.cdc.gov.