CENSUS

an enumeration of people, houses, firms, or other important items in a country or region at a particular time. Used alone, the term usually refers to a population censusthe type to be described in this article. However, many countries take censuses of housing, manufacturing, and agriculture. Censuses, being expensive, are taken only at infrequent intervals: every 10 years in many countries, every 5 years or at irregular intervals in other countries. In noncensus years the population is estimated with the aid of vital statistics if these are sufficiently reliable. For instance, the population in postcensual year X equals the population at the last census plus the births, minus the deaths, plus or minus the net migration during the intervening years.