Census

General Background

Perhaps the most well-known type of census is one that enumerates the population or housing characteristics of a specified country or other politically denned region. Others measure the output in a specified sector of the economy, such as agriculture, transportation, manufacturing, or retail sales. These censuses are typically authorized and funded by the central government of the region covered.

Censuses were first conducted hundreds (Canada, Sweden) and even thousands (China) of years ago in some parts of the world. In many countries, a census is repeated in a fixed cycle, often every 5th (the United Kingdom, Canada, Australia, New Zealand) or 10th (Portugal, Spain, Italy, Poland, Turkey) year. In the United States, the census of population and housing has been conducted every 10th year, beginning in 1790. The U.S. economic census is taken every 5th year.

Historically, the purpose of the census has varied. At first, governing bodies wanted to know the number of people for assessing taxes or determining the number of men eligible for the military. Currently, governments use census data to apportion their legislative bodies, set boundaries for political districts, distribute government funds for social programs, track the nation's economy, measure crops to predict food supplies, and monitor people's commute to work to determine where to improve the region's infrastructure. As a by-product, census lists of households, businesses, or farms are often used as frames for surveys or follow-up studies. Further, the detailed information collected in the census allows for more efficient sample designs and improved estimation in the surveys.

Content and Mode of Collection

The content of a census form can range from a few basic questions to many detailed questions. Indeed, the same census may combine the two approaches. In recent decades, in the U.S. Census of population and housing most households received a “short form” limited to the names, ages, and a few other characteristics of the people living in the household. At the same time, a sample of about 1 in 6 U.S. households received a “long form” that solicited the basic information as well as more detailed data on the residents' demographic and educational background, the housing unit's physical size and structure, and other characteristics. Plans for the U.S. Census in 2010 call for only a short form. The detailed data formerly solicited in the long-form census are now collected in the American Community Survey, a large survey conducted by the U.S. Census Bureau designed to produce estimates at the county level every year. In an economic census, dozens of different forms may be used to tailor the questions to specific types of business.

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