Frequently Asked Questions

Geographic profiles (state, planning region, county, metropolitan/micropolitan area, and city) bring together all data on the website related to a specific geographic area. Although the data sources are not listed directly in the profiles, they are the same sources used in the data by topic dashboards. You can find details about each data source — including the organization providing the data, the specific dataset or program, and additional notes — in the About the Data section. An exception is the Reservation profile, where population data are not available from the Population and Housing Unit Estimates Program. Instead, these data come from the American Community Survey (ACS) 5-year estimates. Legislative District Profiles use data exclusively from the American Community Survey (ACS) 5-year estimates. The data source is listed in each profile, and definitions are provided in the Notes tab.

Demographic profiles (by age, gender, or race/ethnicity) bring together all data on the website related to a specific demographic group. The data sources, though not listed directly in the profiles, are the same sources used in the data by topic dashboards. For more information about the data sources — including the organization providing the data, the specific dataset or program, and additional data notes — visit About the Data.

Each dashboard lists its data sources in the bottom left corner. There you will find:

• The organization providing the data (e.g., U.S. Census Bureau, U.S. Bureau of Economic Analysis, Centers for Disease Control and Prevention [CDC]);
• The specific program or dataset (e.g., American Community Survey, Population and Housing Unit Estimates Program, Regional Economic Accounts, Behavioral Risk Factor Surveillance System [BRFSS]); and
• Additional details when needed, such as the data vintage year for the population estimates or whether ACS data are 1-year or 5-year estimates.

For more information, visit About the Data, where we provide further details about each data source, definitions, and additional data notes.

Sampling error in data occurs when estimates are based on a sample population. The margin of error (+/-) represents the estimated size of sampling error associated with the estimate. When possible, NDCompass presents the margin of error in its data visualizations, which can be viewed by hovering over the charts or tables. For example, the American Community Survey, which is used extensively throughout NDCompass, publishes a margin of error with a 90% confidence level. This is the range in which the true data value will fall 90% of the time (i.e., nine times out of 10). For example, given a data estimate of 49% with a margin of error of +/-1%, one can be 90% confident that the true percentage lies between 48% and 50%. In general, margins of error increase as the size of the population or geographic area decreases. When viewing data for small groups or small geographies, NDCompass encourages users to review the margin of error and interpret estimates with caution. To highlight this, data with large margins of error are displayed in a different color in tables and charts and are accompanied by a note of explanation.

In the Population topic on the NDCompass website and the population sections of the Geographic and Demographic Profiles, all data comes from Population and Housing Units Estimates Program. The U.S. Census Bureau produces various data estimates for population counts through programs like the Decennial Census, the American Community Survey, and the Population and Housing Unit Estimates Program. Every ten years, the Decennial Census provides the official and most accurate population count for each U.S. jurisdiction as of April 1 of each census year (e.g., 2000, 2010, 2020). The American Community Survey provides estimates of the population and various demographic, economic, and health measures. Because estimates are from survey data (i.e., a sample of the entire population), estimates are accompanied by Margins of Error (MOEs). In addition, data for geographies with population less than 65,000 people are available only as 5-year estimates, which are based on 5-year pooled data, which more likely to mask rapid changes from year to year. The Population Estimates Program is the official source for annual population totals between decennial censuses. Annual estimates are based on the decennial census and are calculated based on administrative records (births, deaths, migration), to serve as the best representation of a single year's population (as of July 1 every year) and to provide a consistent reference point across years.  NDCompass uses data from the Population and Housing Unit Estimates Program for population counts—even for decennial years. Although the Decennial Census provides the most accurate population counts for decennial years, the July 1 estimates from the Population and Housing Unit Estimates Program better reflect the average population over the course of a year and offer more consistent reference point across years. These estimates are available annually for all geographic levels and unlike ACS data, are not accompanied by MOEs.