Collection
National population statistics are usually collected by conducting a census. However, because these are usually huge logistical exercises, countries normally conduct censuses only once every five to 10 years. Even when a census is conducted it may miss counting everyone (known as undercount). Also, some people counted in the census may be recorded in a different place than where they usually live, because they are travelling, for example (this may result in overcounting). Consequently, raw census numbers are often adjusted to produce census estimates that identify such statistics as resident population, residents, tourists and other visitors, nationals and aliens(non-nationals). For privacy reasons, particularly when there are small counts, some census results may be rounded, often to the nearest ten, hundred, thousand and sometimes randomly up, down or to another small number such as within 3 of the actual count.
Between censuses, administrative data collected by various agencies about population events such as births, deaths, and cross-border migration may be used to produce intercensal estimates.
Read more about this topic: Population Statistics
Famous quotes containing the word collection:
“We’ll never know the worth of water till the well go dry.”
—18th-century Scottish proverb, collected in James Kelly, Complete Collection of Scottish Proverbs, no. 351 (1721)
“The Nature of Familiar Letters, written, as it were, to the Moment, while the Heart is agitated by Hopes and Fears, on Events undecided, must plead an Excuse for the Bulk of a Collection of this Kind. Mere Facts and Characters might be comprised in a much smaller Compass: But, would they be equally interesting?”
—Samuel Richardson (1689–1761)
“You know, many people believe that we archaeologists are just a collection of old fogies digging around in the ruins after old dried up skulls and bones.”
—Griffin Jay, and Harold Young. Stephen Banning (Dick Foran)