III.

Conducting a Census

Most nations create a permanent national statistical agency to take the census. In the United States, the Bureau of the Census (Census Bureau), an agency of the Department of Commerce, conducts the national population census and most economic censuses. In Canada, the Census Division of Statistics Canada is responsible for taking censuses.

Conducting a census involves four major stages. First, the census agency plans for the census and determines what information it will collect. Next, it collects the information by mailing questionnaires and conducting personal interviews. Then the agency processes and analyzes the data. Finally, the agency publishes the results to make them available to the public and other government agencies.

A.

Planning the Census

Census agencies must begin planning for a census years in advance. One of the most important tasks is to determine what questions will appear on the census questionnaire. Census agencies usually undertake a lengthy public review process to determine the questions to be asked. They conduct public meetings, consider letters and requests from the general public, and consult with other government agencies and special advisory committees. In the United States, census questions must be approved by Congress and the Office of Management and Budget. In Canada, questions must be approved by the governor-general on the recommendations of the Cabinet.

The questions included on census forms vary from nation to nation depending on the country’s particular political and social history and current conditions. Most censuses request basic demographic information, such as the person’s name, age, sex, educational background, occupation, and marital status. Many censuses also include questions about a person’s race, ethnic or national origin, and religion. Further questions may ask the person’s place of birth; relationship to the head of the household; citizenship status; the individual’s or the family’s income; the type of dwelling the household occupies; and the language spoken in the household.

Questions that are routine in one nation may be seen as quite controversial in another, depending on the history of the country. The United States census does not ask about religious affiliation because such a question is considered a violation of the First Amendment right to freedom of religion or an invasion of privacy. Other nations, such as India, do collect such information. Questions on the number of children born to a woman were quite controversial in China in recent years because of government efforts to limit families to having only one child. In the United States, asking a question on income was considered controversial in 1940 when it was first asked. It is no longer considered as objectionable. Questions change in response to public debate about the state of society. For example, Americans wanted to know which households had radios in 1930, and the census introduced questions on housing quality in 1940. Canadians have recently begun to ask census questions on disability status and on the unpaid work done in the home.

Besides determining the content of the census, census agencies must make many other preparations. Staffing is a major concern for census agencies because censuses in most countries require a huge number of temporary workers to collect and process data. Consequently, census agencies must begin recruiting and training workers months or years in advance. For example, the U.S. Census Bureau had to fill 850,000 temporary, short-term positions to conduct the 2000 census. In order to hire and retain enough staff, it had to recruit nearly 3 million job applicants. The majority of temporary workers are hired to go door-to-door to interview households that do not respond to the census questionnaire. In some countries, government employees at a local level, such as schoolteachers, are asked to help conduct the count.

Prior to any census, a census agency must develop an accurate list of addresses and maps to ensure that everyone is counted. The U.S. Census Bureau obtains addresses primarily from the United States Postal Service and from previous census address lists. It also works closely with state, local, and tribal governments to compile accurate lists. Finally, census agencies often conduct an extensive marketing campaign before Census Day to remind the general population about the importance of responding to the census. This campaign may involve paid advertising, distributing materials by direct mail, promotional events, and encouraging media coverage of the census.

B.

Collecting the Information

Until relatively recently, population censuses were taken exclusively through personal interviews. The government sent enumerators (interviewers) to each household in the country. The enumerators asked the head of the household questions about each member of the household and entered the person’s responses on the census questionnaire. The enumerator then returned the responses to the government. Today, many censuses are conducted primarily through self-enumeration, which means that people complete their own census questionnaire. Self-enumeration reduces the cost of a census to the government because fewer enumerators are needed to conduct interviews. In addition, the procedure provides greater privacy to the public and generally improves the accuracy of responses, because household members can take more time to think over the questions and consult their personal records.

A country conducting a census chooses a collection technique based on its social and political traditions and technological capacities. The United States census is highly automated and has been conducted primarily by mail since 1970. For the 2000 U.S. census, the Census Bureau offered many people the option of answering their questionnaires through the bureau’s Web site. Canada began to use self-enumeration in 1971. Today the Canadian government sends enumerators to deliver the census form to each household; the household head fills it out and sends it back to the government. In both the United States and Canada, enumerators are sent to follow up on households that do not mail back the census questionnaire. Other nations continue to conduct censuses only through direct enumeration. Some, such as Turkey, require people to stay home on Census Day to await the census taker.

Census agencies make a special effort to count people who may not receive a questionnaire by mail or who have no permanent address. For example, the U.S. Census Bureau sends census takers to interview people at homeless shelters, soup kitchens, mobile food vans, campgrounds, fairs, and carnivals. It consults with experts to find migrant and seasonal farmworkers. The bureau works with the Department of Defense and U.S. Coast Guard to identify people living on military installations or ships. The Census Bureau also counts military personnel and federal civilian government employees and their families who are living overseas. Finally, the agency distributes census questionnaires to people living in group quarters, such as college dormitories, nursing homes, hospitals, prisons and jails, halfway houses, youth hostels, convents and monasteries, and women’s shelters.

In the United States, Canada, and other countries, households receive either a short or long census questionnaire. Most households receive the “short form,” a brief set of questions on basic characteristics such as name, age, sex, racial or ethnic background, marital status, and relationship to the household head. But a small sample of households receives the “long form,” which asks many other detailed questions. These may include questions about the individual’s educational background, income, occupation, language knowledge, veteran status, and disability status as well as housing-related questions about the value of the individual’s home, the number of rooms and bedrooms in it, and the year the structure was built. The statistical technique of sampling—asking questions of only a representative sample of the population—allows census agencies to collect this detailed information without placing an undue burden on the population or creating an excessive cost to the government. About one in six households in the United States and one in five households in Canada receives the long form. These sample sizes are large enough to produce reliable information about the population characteristics of neighborhoods, regions, states or provinces, and the country as a whole.

C.

Processing and Analysis of Data

For most of the 19th century in the United States and Canada, census data were tabulated and compiled by hand, without the aid of machines. Manual processing was very slow, and some figures were obsolete by the time they were published. The invention of mechanical tabulating devices in the late 19th century made processing of the data much faster and improved the accuracy of the results. Today, census questionnaires are processed primarily on computers and electronic equipment. Besides speeding the processing of results, computers have made it possible to perform sophisticated analyses on the data and to draw correlations between various social and economic characteristics of the country. For example, using census data, statisticians can easily determine the number of people living in Houston, Texas. But they can also determine the number of Houston women between the ages of 25 and 30 who have completed high school and are currently employed.

To process the data from hundreds of millions of paper questionnaires, the U.S. Census Bureau employs an advanced system that scans every questionnaire into an electronic image. Then the images are analyzed by computer software that can recognize when a check-box item on the questionnaire has been marked with a pencil or pen. Optical character recognition software analyzes handwritten responses on the questionnaire and translates them into electronic data. Once in electronic form, the data can be analyzed and turned into statistics. Unreadable or ambiguous responses are checked by census clerks and manually keyed into the computer.

D.

Publication of Results

U.S. and Canadian censuses publish only general statistical information and keep individual responses confidential. By law, the U.S. Census Bureau and Statistics Canada are prohibited from releasing individual responses to any other government agency or to any individual or business. Census workers in both countries must swear under oath that they will keep individual responses confidential. Employees who violate this policy face a monetary fine and possible prison term. If an individual’s personal data were not kept confidential, people might refuse to participate in the census for fear that their personal information would be made public or used by the government to track their activities. In the United States, individual census responses are stored at the National Archives. After 72 years, the original forms are declassified and opened to the public. These original responses are frequently used by people researching the history of their families or constructing genealogies. In Canada, census responses from 1906 and later are stored at Statistics Canada. Microfilmed records of census responses from 1901 and earlier are stored at the National Archives of Canada; these are the only individual census responses currently available for public use.

Until the 1980s, census agencies published their results in large volumes of numeric tables—sometimes numbering in the hundreds of volumes. Today, the majority of census data is distributed electronically, either through the Internet or on CD-ROM, diskette, or magnetic tape. The Web sites of the U.S. Census Bureau and Statistics Canada provide online access to hundreds of statistical publications and data sets. The U.S. Census Bureau planned to disseminate results from the 2000 population census primarily via its Internet site. Both the U.S. Census Bureau and Statistics Canada continue to distribute printed publications for the most commonly requested demographic information. The Statistical Abstract of the United States, published annually by the Census Bureau, is an important statistical compendium on the social, political, and economic aspects of life in the United States. This publication includes data from decennial censuses as well as from other sources, such as surveys taken between censuses. Statistics Canada publishes a similar annual volume on Canadian statistics called the Canadian Year Book.