In ancient times, collection of statistics was little more than a simple head count. Today it is a process of great sophistication. A key data source is the national census, conducted in many countries every 10 years. Census data provides a valuable source of statistical information about the current state of a country and its people. By comparing one set of results with another, significant long-term changes in national life can be monitored.
Sample surveys are another key data source.
Sampling, if scientifically conducted, can produce almost as accurate results as a complete count. Official, continuous surveys are a key source of statistics essential for monitoring social and economic trends. Such surveys can and do in many countries monitor such things as the size and structure of the labour force and the activities of households eg spending patterns, family structure, housing conditions, education, health The more sophisticated can be adapted to changing social trends. Another important data source can be statistics linked to a country s administrative system population registers, taxation information, records of international trade and VAT etc. The Scandinavian countries in particular have been leaders in this field.