What is a Census and Why Does it Matter? Statistics in the Real World

What is a Census and Why Does it Matter? Statistics in the Real World
What is a Census and Why Does it Matter? Statistics in the Real World

Websites, social media, and your mailbox were filled with messages that urged you to respond to the census survey, but can you actually define census? Is it just about estimating population size or is there more to it? How are results collected and what impact do census statistics have on our daily lives?

US Census Form in Spanish

What Is a Census Anyway?

If we were asked to define census, most of us probably could offer an answer that is reasonably close. We know a census is a government-led effort to determine how many people live in a given area.

But identifying a true census definition requires an understanding of the key principles that distinguish a census from other ways of counting or estimating. The United Nations recognizes the importance of census statistics worldwide and lists five parameters for a valid census, including:

1) Individual enumeration (source)

2) Universality within a defined territory

3) Simultaneity

4) Defined periodicity

5) Small area statistics

Men and Women - Symbols standing on a colored pie chart

Individual Enumeration

In a valid census, every individual is counted separately and each individual’s characteristics are recorded separately. A census is more than estimating population size. A census is an effort to identify and count each and every individual.

Crowd on sidewalk

Universality Within a Defined Territory

The census covers a clearly defined territory—for example, the entire country—and includes every person present or living within its scope.


Each person is counted at the same time. Obviously it is not generally possible to conduct a census all in one day, but as an example, census questions often ask who was residing in each household on a given day. Usually a day during the time the census is being taken is chosen, and everyone responding to the census answers who was living in their household on that day.

Census keywords with hand

Defined Periodicity

The census is taken at regular defined intervals, usually every 10 years. An individual census has a certain amount of value, but that value increases significantly when the data from multiple censuses can be compared over time.

Small Area Statistics

The census collects data about the number of people and characteristics of the population down to the lowest appropriate geographic level. In other words, a census will not simply tell us how many and what kind of people live in a country. A census will produce more detailed information about people and characteristics within regions, states and cities.

Magnifying glass with statistical evaluation

One More Distinction: Sample vs Census

Often data and statistics are derived from other kinds of demographic studies, most notably, sampling. While a census identifies every member of the population of interest, sampling includes only a small segment of the group (source).

For example, a census counts all of the men in Texas and records their ages. A sample might randomly select 1,000 men in Texas and ask each man his age. The sample could offer an estimate of how many men in Texas are over 50 while a survey would identify exactly how many men in Texas are over 50.

In other words, a census is generally more accurate and ultimately more useful than a sample study.

Hand with pen filling out census form

How are U.S. Census Statistics Collected?

The United States census meets all five of the criteria identified by the UN, collecting data on each resident of the country on April 1 every ten years ending in zero (source). The U.S. Census Bureau also collects more specific data about each state and city.

What is the Census Bureau?

The Census Bureau is a federal agency whose “mission is to serve as the nation’s leading provider of quality data about its people and economy” (source). In addition to conducting the national census every ten years, the Census Bureau collects and manages data on an ongoing basis, including the following:

  • American Community Survey (ACS),
  • Census of Governments,
  • Economic Census, and

Other surveys and programs (source).

Census envelope

How Does the Census Bureau Collect Data?

While U.S. residents are required by law to participate in the census, counting over 300 million people is no small chore. The Census Bureau works to employ the most effective and efficient methods available to reach every individual in the United States. Most U.S. residents will encounter multiple appeals to ensure their household participates using one of the three primary avenues:

  1. mail response census form
  2. phone questionnaire
  3. online census form

Questionnaires in each of those formats are available in over a dozen different languages.

Census meeting led by a woman

Unique Census Examples

Since the goal of a census is a full and accurate count, the Census Bureau is equipped to locate and identify individuals who cannot or will not respond to traditional methods (source). The Bureau appoints administrators to assist with gathering data on persons living in group living arrangements, such as the following:

  • College/university student housing (i.e., dorms, residence halls, etc.)
  • Residential treatment centers
  • Skilled nursing facilities
  • Group homes
  • Military barracks
  • Correctional facilities
  • Maritime and military vessels

The census even accounts for individuals experiencing homelessness, a population that is notoriously difficult to survey with accuracy. The Census Bureau works with agencies servicing homeless populations and even conducts events intended to encourage homeless men and women to participate (source). These efforts are important since census outcomes affect decisions about and funding for programs designed to serve each of these populations.

Crowd of people shot from above

Why Does the Census Matter?

Knowing basic census statistics satisfies our curiosity about how many people share our space. Every ten years we get a clear picture of national population changes. The last census in 2010 found that 308.7 million people live in the United States (source). That number has grown steadily since the middle of the 20th century.

  • Between 1950-1960, the U.S. population increased by 28 million or 18.5 percent
  • Between 1960-1970, the U.S. population increased by 23.9 million or 13.3 percent
  • Between 1970-1980, the U.S. population increased by 23.3 million or 11.5 percent
  • Between 1980-1990, the U.S. population increased by 22.2 million or 9.8 percent
  • Between 1990-2000, the U.S. population increased by 32.7 million or 13.2 percent
  • Between 2000-2010, the U.S. population increased by 27.3 million or 9.7 percent

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The Census Bureau is also regularly estimating population size and growth and in 2019 estimated the U.S. population to be 328.2 million. That represents a growth rate of 6.3 percent since the 2010 census. Projections suggest the 2020 census will be the second straight to show a slowing growth rate in the nation’s population.

People reviewing census statistics

The Census Provides a Deep Well of Crucial Statistics

Since the census goes beyond sampling and identifies every individual in the country along with detailed information about each person, it has immense statistical value. The field of statistics identifies data collected in the census and uses math to interpret the data. Those statistics then can be studied and used for a virtually endless number of real-world applications.

In addition to providing specific information and statistics for a given census year, census data is also relevant in non-census years. Using the precise results of a census as a baseline, statisticians are able to create more accurate models and projections for non-census years (source). In other words, a census makes other forms of information gathering about a population of interest more reliable and useful.

All of this statistical work is ultimately what gives the census meaning. Census statistics have important implications for virtually every aspect of daily life, including the following (source):

  • Allocating political power
  • Distribution of federal funds through funding formulas
  • Civil rights enforcement
  • Business applications
  • Post-Census population estimates and projections
  • Providing weights for sample surveys
  • Providing denominators for rates
  • Community planning
  • Economic and social science research

Consider a few key examples of how census statistics find vital real-world application:

US Congress Chamber with officials

The Census Determines Congressional Representation

One of the most obvious and important applications of census statistics is in the ongoing forming and reforming of representative government in the United States. Every ten years census results are used to determine how many of the 435 seats in the House of Representatives are allocated to each state. New congressional and state legislative districts are also drawn based on census results (source).

Based on the 2010 census:

  • Texas gained four seats in the House
  • Florida gained two seats in the House
  • Five states gained one seat in the House
  • Seven states lost one seat in the House
  • Two states lost two seats in the House

This reallocation of representation is important for residents of affected districts. It also impacts the changing balance of power among different regions of the country. Over the last century, the South and the West have steadily gained seats in the House while the Northeast and Midwest have seen their percentage of the 435 seats decrease.

The census also both impacts and informs us regarding changes in the size of each district represented by a single congressman. After the 2010 census, the average congressional district contained 710,7676. That meant congressional districts more than tripled in size over the previous century; after the 1910 census, districts included an average of 210,328 people (source).

Redistricting is the process of revising the geographic boundaries of areas from which people elect representatives to the U.S. House of Representatives, a state legislature, a county or city council, a school board, etc. By law, redistricting data must be submitted to the states by April 1 of the year after the census.

Schoolchildren leaving school

The Census Directs Hundreds of Billions of our Tax Dollars

The census is one of the primary tools leaders at all levels of government use in developing crucial economic, legal and social policies. Statistics derived from the census are key in planning and funding programs  that affect the lives of millions of Americans, including the following(source):

  • Schools
  • Health clinics and hospitals
  • Senior citizens services
  • Roads and transportation infrastructure
  • Child protection and welfare
  • Medicare and Medicaid
  • Headstart and other educational resources
  • Emergency services and law enforcement

Geographic data from the census help civic leaders determine existing needs for vital services and programs. Projections based on census statistics also enable decision makers to anticipate areas where needs will emerge.

Since census statistics reveal more than population numbers, planning also can account for demographic information such as income, gender, age and education level. These dynamics are essential in the creation of efficient and effective public policy.

The time between each census makes each census year all the more important. Whether or not they realize it, millions of Americans have anticipated the 2020 census, as it will determine how hundreds of billions of dollars are spent to serve and improve our communities.

People using a point-of-sale system at a coffee shop

The Census Has a Foundational Role in Business and Daily Life

While it’s easy to focus on the importance of the census for various levels of government, it is equally significant for private life and enterprise. Even beyond the impact of government decisions and programs, census statistics impact the planning and decisions made by businesses and individuals.

Consider one simple example:

Jennifer and Britt have saved money for years to open a vintage record store. They know their small town cannot support the venture, so they study nearby cities. Census statistics enable them to select a mid-sized city that has a growing population of their target market: young professionals with moderate to high income.

They also study census business statistics to identify areas already populated with other businesses catering to their primary demographic. This information not only enables them to avoid direct competitors nearby but identify a partnership with a local coffee shop looking for a tenant for an adjoining storefront.

Britt and Jennifer also have two children, so before moving, they study statistics about housing and schools to determine the best place to buy a home.

Whether or not we realize it, the census exerts influence on many of our daily decisions, and statisticians are at the forefront of utilizing census data to improve lives.

People reviewing statistics on electronic wall device

What Does it Take to Put Census Statistics to Meaningful Use?

The Census is one of many opportunities for statisticians to thrive and contribute to our communities. It’s also just one example of why employment for mathematicians and statisticians is expected to grow much faster than overall projected occupational growth (source).

Also true: Those jobs usually require a master’s degree.

Are you interested in exploring the possibilities of this promising career? Start your career with an online Master’s in Applied Statistics.

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