Statistics are a set of numerical data. They relate to a particular characteristic in an enquiry. Collection of these facts and figures forms the beginning of the enquiry. The person who collects the information is called the Investigator or enumerator. One who provides the information is known as the informant or the respondent. The whole process of collecting, counting and systematic recording of the information is called ‘collection of data’. The entire structure of the statistical enquiry depends on the systematic collection of data.
Collection of data, as it seems, is not the beginning of any statistical enquiry. Before actually collecting data, the investigator should carefully examine a set of factors, called the “Preliminaries to data collection” It includes,
(i) The nature and scope of the enquiry
(ii) The objective of the enquiry.
(iii) Sources of information.
(iv) Availability of funds and time
(v) Degree of accuracy desired and
(vi) Statistical units to be used
Data can be collected in different ways. The methods used and the source of information largely depend upon the preliminaries to data collection.