Previous Article – Nature, Scope & Limitations of Statistics
Collection of data
For studying a problem statistically, first of all, the data relevant thereto must be collected. The numerical facts constitute the raw material of the statistical process. The interpretation of the ultimate conclusion and the decisions depend upon the accuracy with which the data are collected. Unless the data are collected with sufficient care and are as accurate as is necessary for the purposes of the inquiry, the result obtained cannot be expected to be valid or reliable.
Before starting the collection of the data, it is necessary to know the sources from which the data are to be collected.
Primary and Secondary Sources
The original compiler of the data is the primary source. For example, the office of the Registrar General will be the primary source of the decennial population census figures.
A secondary source is the one that furnishes the data that were originally compiled by someone else.
If the population census figures issued by the office of the Registrar-General are published in the Indian year Book, this publication will be the secondary source of the population data.
The source of data also are classified according to the character of the data yielded by them. Thus the data which are gathered from the primary source is known as primary data and the one gathered from the secondary source is known as secondary data. When an investigator is making use of figures which he has obtained by field enumeration, he is said to be using primary data and when he is making use of figures which he has obtained from some other source, he is said to be using secondary data.
The choice between Primary and Secondary Data
An investigator has to decide whether he will collect fresh (primary) data or he will compile data from the published sources. The former is reliable per se but the latter can be relied upon only by examining the following factors :—
(i) source from which they have been obtained;
(ii) their true significance;
(iii) completeness and
(iv) method of collection
In addition to the above factors, there are other factors to be considered while making choice between the primary or secondary data :
(i) Nature and scope of enquiry.
(ii) Availability of time and money.
(iii) Degree of accuracy required and
(iv) The status of the investigator i.e., individual, Pvt. Co., Govt. etc.
However, it may be pointed out that in certain investigations both primary and secondary data may have to be used, one may be supplement to the other.
Methods of Collection of Primary Data
The primary methods of collection of statistical information are the following :
1. Direct Personal Observation,
2. Indirect Personal Observation,
3. Schedules to be filled in by informants
4. Information from Correspondents, and
5. Questionnaires in charge of enumerators
The particular method that is decided to be adopted would depend upon the nature and availability of time, money and other facilities available to the investigation.
1. Direct Personal Observation
According to this method, the investigator obtains the data by personal observation. The method is adopted when the field of inquiry is small. Since the investigator is closely connected with the collection of data, it is bound to be more accurate. Thus, for example, if an inquiry is to be conducted into the family budgets and giving conditions of industrial labour, the investigation himself live in the industrial area as one of the industrial workers, mix with other residents and make patience and careful personal observation regarding how they spend, work and live.
2. Indirect Personal Observation
According to this method, the investigator interviews several persons who are either directly or indirectly in possession of the information sought to be collected. It may be distinguished form the first method in which information is collected directly from the persons who are involved in the inquiry. In the case of indirect personal observation, the persons from whom the information is being collected are known as witnesses or informants. However it should be ascertained that the informants really passes the knowledge and they are not prejudiced in favour of or against a particular view point. This method is adopted in the following situations :
1. Where the information to be collected is of a complete nature.
2. When investigation has to be made over a wide area.
3. Where the persons involved in the inquiry would be reluctant to part with the information.
This method is generally adopted by enquiry committee or commissions appointed by government.
3. Schedules to be filled in by the informants
Under this method properly drawn up schedules or blank forms are distributed among the persons from whom the necessary figure are to be obtained. The informants would fill in the forms and return them to the officer incharge of investigation. The Government of India issued slips for the special enumeration of scientific and technical personnel at the time of census. These slips are good examples of schedules to be filled in by the informants.
The merit of this method is its simplicity and lesser degree of trouble and pain for the investigator. Its greatest drawback is that the informants may not send back the schedules duly filled in.
4. Information from Correspondents
Under this method certain correspondent are appointed in different parts of the field of enquiry, who submit their reports to the Central Office in their own manner. For example, estimates of agricultural wages may be periodically furnished to the Government by village school teachers.
The local correspondents being on the spot of the enquiry are capable of giving reliable information.
But it is not always advisable to place much reliance on correspondents, who have often got their own personal prejudices. However, by this method, a rough and approximate estimate is obtained at a very low cost. This method is also adopted by various departments of the government in such cases where regular information is to be collected from a wide area.
Questionnaire in charge of Enumerations
A questionnaire is a list of questions directly or indirectly connected with the work of the enquiry. The answers to these questions would provide all the information sought. The questionnaire is put in the charge of trained investigators whose duty is to go to all persons or selected persons connected with the enquiry. This method is usually adopted in case of large inquiries. The method of collecting data is relatively cheap. Also the information obtained is that of good quality.
The main drawback of this method is that the enumerator (i.e., investigator in charge of the questionnaire) may be a biased one and may not enter the answer given by the information. Where there are many enumerators, they may interpret various terms in questionnaire according to their whims. To that extent the information supplied may be either inaccurate or inadequate or not comparable. This drawback can be removed to a great extent by training the investigators before the enquiry begins. The meaning of different questions may be explained to them so that they do not interpret them according to their whims.
Drafting the Questionnaire
The success of questionnaire method of collecting information depends on the proper drafting of the questionnaire. It is a highly specialized job and requires great deal of skill and experience. However, the following general principle may be helpful in framing a questionnaire :
1. The number of the questions should be kept to the minimum fifteen to twenty five may be a fair number.
2. The questions must be arranged in a logical order so that a natural and spontaneous reply to each is induced.
3. The questions should be short, simple and easy to understand and they should convey one meaning.
4. As far as possible, quotation of a personal and pecuniary nature should not be asked.
5. As far as possible the questions should be such that they can be answered briefly in ‘Yes’ or ‘No’, or in terms of numbers, place, date, etc.
6. The questionnaire should provide necessary instructions to the Informants. For instance, if there is a question on weight. It should be specified as to whether weight is to be indicated in lbs or kilograms.
7. Questions should be objective type and capable of tabulation.
Specimen Questionnaire
We are giving below a specimen questionnaire of Expenditure Habits or Students residing in college Hostels.
Name of Student ……………………………………..
Class ……………………………………..
State and District of origin …………………………
Age …………………………
1. How much amount do you get from your father/guardian p.m.?
2. Do you get some scholarship? If so, state the amount per month.
3. Is there any other source from which you get money regularly? (e.g. mother, brother or uncle).
4. How much do you spend monthly on the following items :
Rs.
College Tuition Fee ………
Hostel Food Expenses ……..
Other hostel fees ……..
Clothing ……..
Entertainment ……..
Smoking ……..
Miscellaneous ……..
Total ……..
5. Do you smoke?
If so what is the daily expenditure on it?
6. Any other item on which you spend money?
Sources of Secondary Data
There are a number of sources from which secondary data may be obtained. They may be classified as follow. :
1. Published sources, and
2. Unpublished sources.
1. Published Sources
The various sources of published data are :
1. Reports and official publications of-
(a) International bodies such as the International Monetary Fund, International Finance Corporation, and United Nations Organisation.
(b) Central and State Governments- such as the Report of the Patel Committee, etc.
2. Semi Official Publication. Various local bodies such as Municipal Corporation, and Districts Boards.
3. Private Publication of—
(a) Trade and professional bodies such as the Federation of India, Chamber of Commerce and Institute of Chartered Accountants of India.
(b) Financial and Economic Journals such as “Commerce”, ‘Capital’ etc.
(c) Annual Reports of Joint Stock Companies.
(d) Publication brought out by research agendas, research scholars, etc.
2. Unpublished Sources
There are various sources of unpublished data such as records maintained by various government and private offices, studies made by research institutions, scholars, etc., such source can also be used where necessary.
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