ome countries, notably in Scandinavia, now rely on administrative sources such as population registers as a supplement or even as a complete alternative to conducting a national census. Finland, for example, has not had a conventional census since 1980. Instead the Government compiles information from around 30 different databases. These include a central population register which provides essential demographic and housing data, with other registers providing linked information on economic and social aspects of the population. This approach has a number of advantages over a conventional census. These include cost effectiveness the data are already being collected for other purposes. By contrast the design and implementation of a national census involves a massive additional outlay of public money. In addition administrative lists are continually updated, unlike the census which provides a snap-shot of the population at a single point in time. Demographic and social changes can quickly make census data unreliable as a record of population, particularly at the local level. However most countries (including Britain) currently lack administrative records comprehensive enough to replace the census, which is likely to remain a key requirement for the majority of countries for the foreseeable future.