Shanda Burrell, 32, holds a U.S. census sign during a rally by census advocates in Charlotte, N.C., on April 10, 2010. The rally, held at a local mosque, was aimed at convincing Muslims and other Americans to fill out the 2010 census form. (Jason E. Miczek/Associated Press)

United States

The United States conducts it national census every 10 years, most recently in 2010.

In 2003, the U.S. Census Bureau researched the idea of making its long-form survey, now known as the American Community Survey, voluntary for people to complete.

Former U.S. Census Bureau director Kenneth Prewitt told CBC News that making the long-form census voluntary would have led to a drop in the number of people who would respond. (CBC)But the bureau found that making that survey voluntary would result in fewer people filling it out, "which [would] cost money for the country to get an accurate census," said Kenneth Prewitt, the census bureau's former director.

"It simply makes it a less accurate portrait of the American public. It requires you to use what we call 'weighting factors' to get it back proportionately to what it should have been," Prewitt, now a public affairs professor at Columbia University, told CBC News in an interview.

"Statistically, that just slightly weakens the data. That doesn't cripple it, doesn't make it unusable, but it simply makes for less useful data, less accurate data than you need to run a big, complicated economy and government, as both Canada and the United States do."

The American Community Survey is sent to a sample of about three million addresses across the country, according to the U.S. Census Bureau.

The bureau also delivers a short survey to every household in the nation. It is mandatory to fill out the short questionnaire, which asks 10 basic questions about the age, gender and race of people in a given household. Census surveys cannot be completed online.

United Kingdom

The Office for National Statistics has carried out a population census in Great Britain every 10 years since 1801, except in 1941 during the Second World War.

The British government is hoping that the next census, slated for 2011, will be the last of its kind in that country.

Francis Maude, the minister responsible for Britain's cabinet office, has said the traditional census is costly to carry out, with the results often incomplete and outdated by the time they are published.

The Office of National Statistics has been looking at census alternatives through its Beyond 2011 project.

"It is clear rapid changes in society and greater availability of alternative data about the population are leading to new requirements for population statistics," the Beyond 2011 website states.

"Data users want a greater range of statistics to be available more frequently, to provide an accurate picture of population change."

European Union

EU member nations are planning to hold a pan-European census in 2011, thanks to an EU regulation that was passed in 2008. Member countries are organizing censuses to be held that year, with the results to be ready by March 2014.

The 2011 EU-wide census will include questions about the age, gender, marital status and employment status of those in a given household, as well as questions about the size and density of that household.

Some EU member nations, like Germany and the Scandinavian countries, use a register-based census model, in which existing data is collected from administrative registries, such as municipalities and federal employment agencies. Collecting such data reduces the need to survey residents through interviews or questionnaires.

Brazil

Census field staff in Brazil will use these portable computers when they start enumerating households in August. (Brazilian Institute of Geography and Statistics)While the United States struggle with moving census-taking methods into the computer age, Brazil is using two innovations in its 2010 census, slated to begin in August.

The Brazilian Institute of Geography and Statistics is equipping its enumerators with GPS-enabled portable computers that will transfer collected census data faster through a national network.

Brazilian residents can also answer census questionnaires online, through a special encrypted website.

About 58 million households will be surveyed in Brazil's census, which is held every 10 years.

India

In addition to carrying out its 15th national census in 2011, with surveys to be sent out about people and housing, India is also creating a National Population Register that will include, among other details, photographs and biometric information such as fingerprints and possibly iris information of everyone over the age of 15.