What is a census-able way to run a census?

Posted 23/04/2015 by Aaron Greenup

This is part of a series of FlagPosts exploring what the Census is, why it’s important, how other countries run censuses and what the alternatives—either officially proposed or informally discussed—may be (Part 1: Potential changes to the Australian Census: could it kill the goose that lays the statistical golden egg?).

Countries approach the compilation of demographic statistics in a range of ways. However, a census is nearly always an important part of this process. That said, there are many different approaches; these extend beyond just the timing of the census (5 or 10 years) and include the subject areas covered and the methods used to collect information.

When considering the benefits or drawbacks of any potential changes to the way the Australian Bureau of Statistics (ABS) conducts the Census, it’s useful to understand what approaches are used internationally and the relative advantages and disadvantages of each approach.

Advantages and disadvantages of different approaches are summarised below, and Table 1 provides examples of countries using these approaches. Further information is available from the publication: Conference of European statisticians Recommendations for the 2010 Censuses of Population and Housing and the National Statistical agencies responsible for the each countries census (see Table 1 and Footnotes for further information).

Traditional census

Information on all persons in a country on census night is collected at the same time (or within a short period of time). This includes data on basic demographics, as well as social and economic data.

Advantage/s

Provides a snapshot of the entire population at a fixed point in time
Data is available for very fine levels of geography.

Disadvantage/s

Traditional censuses are usually very expensive and complex to run
Data is often ‘out-of-date’ well before the next census is run
There are some limitations to content because of the length of the survey.

Traditional census with yearly updates

This is similar to the traditional approach where basic demographic data is collected on all persons in a country on census night. However, more detailed data on the social and economic circumstances of the population is not collected at census time. Instead, a separate sample survey is run in non-census years to collect this information.

Advantage/s

More frequent and up-to-date information about the social and economic characteristics of the population are available than through a traditional census
The operational risks and complexity associated with running a census are somewhat reduced, as only basic information is collected at census time.

Disadvantage/s

The level of detail available from a sample survey may not be the same as if the data was collected from a census.

Register based census

A strictly register based census is built around existing data on the population. The type of data used for population registers is commonly referred to as administrative data. It is usually stored by governments for purposes such as the administrative functions of taxation, health and social security, as well as other various functions of government.

Advantage/s

Cost associated with a register based census is much lower than for a traditional census
Data from a register based census is more timely and up-to-date.

Disadvantage/s

The breadth of information available from a register based census is limited to the data contained on the available registers
Registries are impacted by changes in legislation and administrative processes which may affect what data is available.

Register based with survey data (sample and complete enumeration)

A register based census approach supplemented with data from smaller sample surveys and/or complete enumeration, addresses the problem of being restricted to information available from administrative sources. It can also help ensure the register based population counts are of the highest possible quality.

Advantage/s

Costs associated with a register based census and smaller sample surveys is much lower
High quality population counts.

Disadvantage/s

Requires more processing of data than a traditional census as survey data needs to be ‘weighted’ to represent the total population
More expensive than a solely register based census.

Rolling census

The census is run as a continuous cumulative survey, run over a longer period than a traditional census.

Advantage/s

Potential for more regular updates to data
Enables incremental improvements to methods and technology used to conduct the census to be implemented more easily.

Disadvantage/s

Comparisons between areas or different populations are more difficult as data is collected at different times. Unlike in a traditional census approach, it is not a snap shot for a single point in time.

Table 1 - Examples of countries for each census type

Census Type	Example Countries
Traditional census	Australia, Canada, New Zealand, England Ireland and Wales (UK)
Traditional census with yearly updates	United States
Register based census	Norway, Iceland, Sweden, Netherlands, Denmark, Belgium, Austria and Slovenia
Register based with survey data	Germany, Spain, Poland, Lithuania, Latvia and Estonia
Rolling census	France