Following are the differences between primary and secondary data :
- Nature : Primary data is original data and is like raw material for statistical methods, while secondary data is like finished product, as it has already been through statistical procedures.
- Collectors : Primary data is collected by the investigator or his representative, while secondary data is collected by other individuals or institutions earlier and are already published.
- Objective : Primary data is always collected in accordance with the objective of the investigation while secondary data has to be modified according to the objective of investigation.
- Plan : Primary data is collected in a new form by making an independent plan, while secondary data is already available data, i.e. data available in some publication, report and documents is secondary data.
- Time and Money : More time and money is spent in collecting primary data. While less time and money is spent in collecting secondary data.
- Availability : Primary data is collected from the statistical units in the area of invesatigtion while secondary data is collected by other individuals or institutions.
Following are the methods of collecting primary data :
- Direct personal investigation method : This method is suitable for such investigation, where the scope is limited or of local nature and in which more importance is given to accuracy, purity and confidentiality of data. In this method, the investigator himself goes in the area of investigation and establishes personal and direct contact with the person who provides information and collects data on the basis of examination and experience. In a limited area, investigations in context to income-expenditure, conditions of living of workers, educated unemployment, etc. are usually done through this method.
- Indirect oral investigation method : Under this method, information is not obtained from persons who have direct relationship with the problem, rather data is collected by oral questioning of a third parties. This data is indirectly associated with the root problem under investigation. Direct contact is not established with the persons from whom the information has to be obtained. This method is used when the area of investigation is broader.
- Information through local residents and correspondents : Information through local residents and correspondents is the method in which the investigator appoints local residents and special correspondents who send information on the basis of their experience time to time.
- Information through schedules to be filled by the informant method : In this method, the investigator prepares a list of questions associated with the enquiry. These questionnaire are printed and sent by post to those persons from whom the information is to be obtained. Along with these, he also sends a letter of request in which request is made to send them back by a fixed date and to maintain confidentiality.
- Filling of schedules by the enumerators : In this method, a list of questions associated with enquiry is prepared and it is handed over to the enumerators. The enumerators ask related questions from the information providers and write their answers in the list. Enumerators are trained in this work and they are also familiar with the regional language. This method is suitable for places where labour, time and money is available in abundance.
