On August 1, the U.S. Census Bureau will release the 2020 Census Detailed Demographic and Housing Characteristics File B (Detailed DHC-B), adding to what we know about our nation’s diverse population. Last year, through the Detailed DHC-A, we learned about the population size and the number of males and females in certain age categories for about 1,500 detailed race and ethnicity groups and American Indian and Alaska Native (AIAN) tribes and villages. 

Now, we will learn more about the household composition of these groups. For example, the Detailed DHC-B will include information on whether people live in family or nonfamily households and whether they own or rent their homes (we call this “tenure”). 

Similar to the Detailed DHC-A, the amount of information about these topics will vary depending on the size of the group and the geography. This approach allows the Census Bureau to produce as much detail as possible while ensuring confidentiality protections and that the data meet the Census Bureau’s accuracy standards. 

In this blog, we’ll explain what information will be available in the Detailed DHC-B and what to consider when using the data. 

First, let’s walk through the who, what and where.

In terms of who, the Detailed DHC-B data will be available for the household only population because the topics are only about households. Detailed DHC-B data will not be available when the geography you’re interested in only has group quarters, such as college dormitories, military barracks or prisons. 

Next, the data are available based on the detailed race or ethnicity of the householder. For the 2020 Census, the householder is the first adult listed in the household’s census response.

The same 300 detailed race and ethnicity groups and 1,187 AIAN tribes and villages released in Detailed DHC-A will be available in the Detailed DHC-B. If you would like a refresher on what groups are included, check out the blog What You Should Know About the Upcoming Detailed DHC File A. 

In terms of what, the Detailed DHC-B product will provide two types of tables: (1) household type (e.g., family or nonfamily household) and (2) tenure (whether the home is owned or rented). Each table type will also include a count of households. (In the tenure tables, it’s called “occupied housing units.” We talk more about these counts below.) 

The amount of information in each table, beyond the household count, depends on the size of the group and the geography.  

This brings us to where. The Detailed DHC-B data will be available for the nation, states, counties, places, census tracts, and American Indian, Alaska Native and Native Hawaiian (AIANNH) areas. However, the group needs to meet the population threshold to have data available for a given geography.

In short, larger groups receive more household type and tenure information while smaller groups receive less. At the national and state levels, all groups receive a total household count at a minimum. However, many groups do not receive any data for a given county or tract because they do not meet the population threshold.  

Here’s what this means for the two types of tables:

• Household type. Groups receive one of four household type tables depending on their total population size for a given geography. ​The smallest groups receive a table with just the total number of households. ​Larger groups receive a table with two, six or eight household type categories. For example, these categories include counts of family households, married couple family households, nonfamily households, and householders living alone.  

• Tenure. Groups receive one of two tenure tables depending on their total population size for a given geography. ​The smallest groups receive a table with just the total number of occupied housing units. ​Larger groups receive a table with three categories: (1) the number of housing units owned with a mortgage or a loan, (2) the number owned free and clear, and (3) the number that were renter occupied.  

The population thresholds required for each table are available in the fact sheet Detailed DHC-B Adaptive Design Summary, and the final table shells are included on the “Detailed DHC A & B Tables” tab of the 2020 Census Data Product Crosswalk.

Above, we mentioned that both the household type and tenure tables include a count of the total number of households. (The tenure table just uses a different name: “occupied housing units.”) 

One thing to be aware of is that these two numbers likely will not match for a given geography and group. The reason is, we infused statistical noise — small, random additions and subtractions — in the two table types separately. This approach protects the confidentiality of the underlying responses while also providing quality data, but it does cause some inconsistencies in the tables. (Certain inconsistencies were possible in previous 2020 Census data products too, such as those described in the Detailed DHC-A technical documentation.)

Similarly, you will find some other inconsistencies. Examples include:

• Aggregating geographies and groups within the Detailed DHC-B will result in totals that frequently do not match the published count. For example, counties usually do not sum exactly to state totals, and detailed groups usually do not sum to regional groups.

• Since noise is infused separately to each 2020 Census data product, there may be more households for some groups in the Detailed DHC-B than there are people in those groups in the Detailed DHC-A.

• If you add up all the detailed household counts in the Detailed DHC-B, it will not match the major race or ethnicity group in the Redistricting Data (P.L. 94-171) Summary File or the Demographic and Housing Characteristics File (DHC).

With these situations in mind, we encourage you to consider the following guidance when using the Detailed DHC-B data:

• If you need a count of households, use the count from the table with the fewest categories presented. For example, if your group receives the tenure table with three categories and the household type table with six categories, use the total count from the tenure table. The total household (or occupied housing unit) count is calculated by adding up the categories in the table, so the more categories, the more statistical noise in the total count. (If your group receives the tables with just the total count, choose the table that is most relevant for you — household type or tenure. Because there aren’t any other categories to add up, the total household count has the same level of accuracy between the two types of tables.)

• Don’t combine data across the Detailed DHC-A and Detailed DHC-B to calculate average people per household. The Detailed DHC-A includes the group quarters population, which should not be included in people per household calculations. 

• Don’t infer missing data by adding or subtracting published data. These data were suppressed to ensure demographic reasonableness. Inferred totals may be unreliable (such as negative numbers).  

• Use the published counts for the groups and geographies whenever possible, rather than creating custom aggregations, which results in less accurate data. 

• Aggregate the smallest number of items possible. For example, if data for a custom geographic area can be calculated by summing the data across 10 tracts or subtracting the data for two tracts from a county total, subtracting the data for two tracts yields a more accurate result than combining the data across 10 tracts. 

We talked through this guidance in today’s webinar and will have additional guidance available in the product’s technical documentation and a brief on disclosure avoidance in the Detailed DHC-B. For example, the brief will include a section with guidance on calculating percentages, understanding suppressed counts, comparing to other Census Bureau data sources, and aggregating the Detailed DHC-B data. 

We look forward to sharing these household data with you August 1. We’ll release the Detailed DHC-B data on data.census.gov, the Census Bureau's API, and provide a summary file on the FTP site for an easier bulk download. We’ll also provide short videos and how-to guides with screenshots to help you access the data.

For more information about the upcoming release, visit the Detailed DHC-B press kit.