Primary data and Methods of collecting primary data in statistic?

  Primary data:

The data that have been originally collected by someone and no statistical techniques have been applied on such data, are called the primary data e.g. data obtained in census study are called primary data. OR to know the effect of fertilizer on the yield of wheat, then the observations taken on each plot are called primary data.

Methods of collecting primary data:

The methods involved in collecting primary data are described below:

1.                 Direct personal investigation:

In this method the investigation interview. The concerned persons on the spot about the problems under study and record the required information’s personally.

Advantage:

The data obtained by this method are highly accurate and reliable and reliable. The accuracy of the results depends on the efficiency and proper training of the investigator. The investigator should be polite, tactful and conversant. He should mix himself with the people and speak the language of the people. In this way he can get maximum information’s about the problem under study.

Disadvantages:

This methods is very slow, expensive and time consuming and particularly suitable for small scale and secret inquiries. The personal like and dislike of the investigator may surely affect the result.

2.                 Indirect personal investigation:

Sometimes the information’s refuse to give answer to some direct questions, the information’s are then collected by putting some indirect questions on informants OR by interviewing several third persons or witnesses who are expected to know the full knowledge about the problems under study. E.g. when the businessman are reluctant to give information’s about their income to income tax authorities then the authorities (i.e. officers) can get the required information’s from the persons like salesman, clerks etc who directly involve in that business.

Advantages:

This methods saves time and money because only those persons are interviewed who know the full facts. Proper training and tactfulness of the investigator may produce good results.

Disadvantages:

The investigator takes too much time in convincing the persons to supply information’s. In many cases people do not co-operate and refuse to supply the needed information’s.

3.                 Investigators through mail questionnaire:

Under this method a questionnaire (a standard list of questions about a particular problem) is sent by post to persons from when information is to be obtained. These persons are explained the purpose, the scope and importance f the inquiry. They are requested to fill in the questionnaire properly and send it back as soon as possible.

Advantages:

This is less costly and less time consuming. The information’s can be collected from a wide area. A reasonable standard of accuracy is expected by this method.

Disadvantages:

Most of the information’s do not care to fill in the questionnaire and the rate of return is very slow. Some of the information’s return the questionnaire incomplete and full of errors which certainly affect the result.

4.                 Investigation through questionnaire in charge of enumerators:

This method is the most satisfactory and most widely used method of data collection. In this method information’s are collected by appointing trained investigators who go to the information’s with a questionnaire and help them in filling up the relevant columns in the questionnaire.

Advantages:

It is one of the most satisfactory methods of data collection where informants are uneducated. The investigator can explain the purpose of the enquiry and meaning of questions to illiterate persons and thus can get the accurate results. The possibility of non-response is very much low which is most serious in case of mail questionnaire.

Disadvantage:

This method is very expansive and time consuming, because large number of investigators is to be employed. They are to be paid salaries, daily allowances and travelling expenses. In case the informant is not available at his place. Then investigator has to pay two or more visits t get information’s. Thus it is time consuming method.

5.                 Investigation through correspondents:

Under this method, the data collecting agency appoints local agents or correspondents in different areas for collecting and supplying information. They collect the needed data and send the same to the agency for supplying e.g. news paper, magazines etc uses this  methods to get information’s from their correspondents in different fields such as strikes, sports, wars, politics etc.