The activities of an organisation rest upon collection of factual data and information. The statistical investigator collects the primary data from the original sources and secondary data are collected from the published sources. Various methods of collection of primary data are:
(a) Direct personal interview-Under this method, data are collected by the investigator through direct conversation with the people.
(b) Indirect investigation — under this method, the investigator collects information indirectly by the contact of a third party.
(c) Observation and experiment — under this method, information is collected by conducting observation and experiment.
(d) Correspondents — under this method, correspondents are appointed in different localities to collect information.
(e) Questionnaire — under this method, the information is collected by sending a set of questions in questionnaire.
(f) Secondary data are collected from published sources like magazines and periodicals.