What are the Sources of Data?

Sources of Data

Sources of Data can be classified into 2 types. Statistical sources refer to data that are gathered for some official purposes and incorporate censuses and officially administered surveys. Non-statistical sources refer to the collection of data for other administrative purposes or for the private sector.

Q.1- What do you understand by the collection of data? What are the different sources of data?
(A) Collection Of Data
  • Collection of data is the first step of statistical investigation.
  • It involves gathering information to be analyzed for a specific purpose.
(B) Sources Of Data
  • Following are the two sources of data:
  1. Internal Source.
  2. External Source.
(1) Internal Source
  • When data are collected from reports and records of the organization itself, it is known as the internal source.
  • For example, a company publishes its ‘Annual Report’ on Profit and Loss, Total Sales, Loans, Wages etc.
(2) External Source
  • When data are collected from outside the organization, it is known as the external source.
  • For example, if a Tour and Travels Company obtains information on ‘KarnatakaTourism’ from Karnataka Transport Corporation, it would be known as external sources of data.

Types of Data- Primary & Secondary

Q.1- Explain Various Types Of External Data With The Help Of Suitable Examples.
Following Are The Two Types Of External Data:
(A) Primary Data
  • Primary data means ‘First-hand information’ collected by an investigator.
  • It is collected for the first time.
  • It is original and more reliable.
  • For example Population census conducted by the government of India after every 10 years.
(B) Secondary Data
  • Secondary data refers to ‘Second-hand information’.
  • These are not originally collected rather obtained from already published or unpublished sources.
  • For example the Address of a person taken from the Telephone Directory or Phone number of a company taken from ‘Just Dial’.
Q.2- Distinguish Between Primary Data And Secondary Data.
Basis Primary Data Secondary Data
(1) Meaning Primary data are those which are collected for the first time. Secondary data refers to those data which have already been collected by some other person.
(2) Originality Primary data is original because these are collected by the Investigator for the first time. Secondary data are not original because someone else has collected these for his own purpose.
(3) Nature Of Data Primary data are in the form of raw materials. Secondary data are in the finished form.
(4) Reliability And Suitability Primary data are more reliable and suitable for the enquiry because it is collected for a particular purpose. It is less reliable and less suitable as someone else has collected the data which may not perfectly match our purpose.
(5) Time & Money Collecting primary data is quite expensive both in time and money terms. Secondary data requires less time and money so it is economical.
(6) Precaution & Editing No special precaution or editing is required while using primary data as these have been collected with a definite purpose. Both precaution and editing are essential as secondary data were collected by someone else for his own purpose.

Students can also refer to Meaning and Sources of Secondary Data

Methods of Collecting Primary Data

Q.1- Name The Different Methods Of Collecting Primary Data.
Answer: Following Are The Popular Methods Of Collecting Primary Data:
Methods Of Collecting Primary Data
  1. Direct Personal Investigation
  2. Indirect Oral Investigation
  3. Information Through Correspondents
  4. Telephonic Interview
  5. Mailed Questionnaire
  6. The questionnaire filled by enumerators
Q.2- Give The Meaning Of The Following Terms:

(A) Investigator

(B) Enumerator

(C) Informant/respondent

  • One who conducts the investigation i.e. statistical enquiry and seeks information is known as Investigator.
  • It can be an individual person or an organization.
  • Enumerators are the persons who help the Investigators in the collection of data.
  • Informants are the respondents who supply the information to the investigator or enumerators.

Direct Personal Investigation

Q.1- Explain ‘direct Personal Investigation Method’ Of Collecting Primary Data. Also, Discuss Its Merits And Demerits.
(A) Direct Personal Investigation
  • Under this method, the Investigator obtains the first-hand information from the respondents themselves.
  • He personally visits the respondents to collect information (data).
(B) Following Are The Merits Of Direct Personal Investigation:
(1) Reliable And Accurate
  • Data collected are first hand and original in nature. So, these are more reliable and accurate.
(2) Flexibility
  • In this method, questions can be modified according to the level of the respondent or other situations.
(3) Additional Information
  • Some additional information may also be collected along with the required information.
  • This additional information can be used in future investigation.
(c) Following are the demerits of direct personal investigation:
(1) Not Suitable For Wide Area
  • It is not suitable when the area of coverage is considerably wide.
(2) Time-consuming
  • This method is time-consuming as investigator personally visits the various places and meet different people to collect information.
(3) Expensive
  • This method is expensive particularly when the field of investigation is large.
(4) Personal Bias
  • Data collected in this method is subject to personal bias.

Indirect Oral Investigation

Q.1- Explain indirect oral investigation method of collecting primary data. Give its merit and demerits.
(A) Indirect Oral Investigation Under this method, instead of directly approaching the informants, the investigators interviewed several other persons who are directly or indirectly in touch with the informants.
(B) Following Are The Merits Of Indirect Oral Investigation:
(1) Wide Coverage
  • A wide area can be brought under investigation through this method.
(2) Economical
  • It is economical in terms of time, money and manpower.
(c) Following are the demerits of indirect oral investigation:
(1) Indirect Information
  • Since the information is not collected directly from the party, it is doubtful that it will be fully true.
(2) Lack Of Accuracy
  • As compared to Direct Personal Investigation, the degree of accuracy of the data is likely to be lower.
(3) Lack Of Uniformity
  • Information collected from different persons for the same party may not be homogeneous and comparable.
(4) Possibility Of Biased Information
  • Respondent\witness can modify the information according to his personal interest.

Information through Correspondents

Q.1- Explain ‘information through correspondents method’ of collecting Primary data. Give its merit and demerits.
(A) Information Through Correspondents Under this method, local agents or correspondents are appointed and trained to collect the information from the respondents.
(b) Following are the merits of information through correspondents:
(1) Wide Coverage
  • This method is useful where the field of investigation is very wide and the information is to be collected from different parts of the country.
(2) Economical
  • This method is quite economical and time-saving.
(3) Suitable For Special Purposes
  • This method is suitable for some special purpose investigations.
  • It is very useful for collecting information on a regular basis.
(c) Following are the demerits of information through correspondents:
(1) Lack Of Uniformity
  • The information supplied by different correspondents often lacks homogeneity, and hence, not comparable.
(2) Lack Of Reliability
  • Data obtained using this method may not be very reliable because of the possibility of personal bias and prejudice of the enumerator.
(3) Less Accuracy
  • This method cannot be used where a high degree of accuracy is required.
(4) Costly
  • A lot of time & money is spent to collect the information through correspondence.

Telephonic Interviews

Q.1- Explain the ‘telephonic interviews method’ of collecting primary data. Give its merit and demerits.
(A) Telephonic Interviews Under this method, data are collected through an interview over the telephone.
(b) Following are the merits of telephonic interviews:
(1) Wide Coverage
  • This method is useful where the field of investigation is very wide and the information is to be collected from different parts of the country.
(2) Economical
  • This method is quite economical and time-saving.
(3) Reliability
  • The data collected is reliable as it is obtained directly from the party.
(c) Following are the demerits of telephonic interviews:
(1) Limited Use
  • The disadvantage of this method is accessible to people. This method is not possible for people who do not own a telephone or mobile.
(2) Visual Feedback Is Not Possible
  • Telephone Interviews also obstruct visual reactions of the respondents, which become helpful in obtaining information on sensitive issues.

Mailed Questionnaire Method

Q.1- Discuss the ‘mailed questionnaire method’ of collecting primary data. What are its merits and demerits?
(A) Mailed Questionnaire Method
  • Under this method, a questionnaire containing a number of questions related to the investigation is prepared.
  • It is then sent to Informants by post along with the instructions to fill.
  • The Informant after filling up the questionnaire sends it back to the Investigator.
(b) Following are the merits of the mailed questionnaire method:
(1) Wide Coverage
  • This method is useful where the field of investigation is very wide and the information is to be collected from different parts of the country.
(2) Economical
  • This method is quite economical as it requires less money and labour.
(3) Originality
  • The data are very much original because informants are directly involved in the collection of data.
(4) Free From Bias
  • Every question is interpreted by the respondent in his own way. Hence, it is free from the personal bias of the Investigator.
(5) Maintains Secrecy
  • This method is suitable for sensitive questions and maintains the anonymity of respondents.
(c) Following are the demerits of the mailed questionnaire method:
(1) Limited Scope
  • This method is applicable only where respondents are educated.
(2) Less Response
  • Most informants do not return the questionnaire.
  • The informants are least interested in the investigation; hence there is a lack of response from their sides.
(3) Chance Of Misinterpretation
  • Informants may not understand the correct sense of questions, and may not answer such questions. Sometimes, informants may provide vague and ambiguous answers.
(4) Time-consuming
  • The process is time-consuming, particularly when the information is to be obtained by post.
Q.2- What is a questionnaire? State the prerequisites of the good questionnaire.
What are the qualities of a good questionnaire?
(A) Meaning Of Questionnaire The questionnaire is a list or set of printed questions which are filled by the Informants. If it is filled by the Enumerators, it is called a Schedule.
(b) A good questionnaire should have the following characteristics:
(1) Simple & Short Questions Questions should be short, simple and straight forward.
(2) Limited Questions In Proper Order The number of questions should be limited and these should be in a logical order.
(3) Clear Instructions To assist the informant clear instructions should be given wherever required.
(4) Pre-testing To know the shortcomings of Questionnaire, it should be tried on a small selected group.
(5) Avoid Mathematical Calculations Questions containing mathematical calculations should be completely avoided.
(6) Avoid Personal Or Controversial Questions Personal questions affecting sentiments and controversial questions related to religion, politics etc. should be avoided.
(7) Secrecy Assurance Respondents should be given assurance that their response will be not be shared with anyone.
(8) Covering Letter To convey the purpose of and how it will help the parties involved, a precise covering letter should be enclosed.

Questionnaire Filled By Enumerators Method

Q.1- Explain the ‘questionnaires filled by enumerators method’ of collecting primary data along with its merits and demerits.
(A) Questionnaires Filled By Enumerators Under this method, Enumerator personally visits Informants along with a questionnaire, asks questions and note down their response in the questionnaire in his own language.
(b) Following are the merits of questionnaires filled by enumerators:
(1) Accurate And Reliable Since the investigator has direct contact with the respondents, it is possible to get accurate and reliable information.
(2) Better Response The presence of the enumerator may induce the respondents to give information.

So, chances of non-response like in case of Mailed Questionnaire Method are less.

(3) Useful In Case Of Illiterate Respondents Unlike the ‘Mailed Questionnaire Method’, this method can be used even if the respondents are illiterate.
(c) Following are the demerits of questionnaires filled by enumerators:
(1) Costly Method This method is very expensive as expenditure on training; remuneration and conveyance are to be borne by the Investigator.
(2) Time Consuming This method is very time consuming as Enumerator has to visit the informants personally.
(3) Inefficiency & Personal Bias Inefficiency or inability on the part of the enumerators due to lack of proper training, coupled with personal bias may adversely affect the results of the enquiry.

Students can explore this important concept by clicking on this link provided below:

Meaning of Statistical Enquiry, Meaning of Collection of Data and Sources of Data

Collection Of Secondary Data

Q.1- What is secondary data? Briefly discuss the various source of secondary data.
(A) Meaning Of Secondary Data
  • Secondary data refers to those data which have already been collected by some other person or agency and used by us.
(b) sources of secondary data can broadly be classified under two


1. Published sources

2. Unpublished sources

(1)Published Sources Published sources mean data available in printed form. It includes:

  1. Magazines, Journals & Periodicals published by various Government, Semi-government and Private organisations. Like, data related to birth, death, education etc. by the government at various levels; data regarding Prices, Production etc. published by Economic Times, Financial Express etc.
  2. Reports of various Committees or Commissions. Like, report of Pay Commission Report, Finance Commission Report etc.
  3. Reports of International Agencies- Reports are regularly published by agencies like UNO, WHO, I.M.F. etc.
(2) Unpublished Sources
  • All statistical material is not always published.
  • This category included. Records maintained by various government and private offices.ii. Research studies were done by scholar students or some institutions.iii. Reports prepared by Private Investigation companies etc. Such sources can also be used depending upon the need.
Q.2- What precautions shall we take while using secondary data? Explain.
Following are the main precautions to be taken while using secondary data:
(1) Reliable Agency
  • We must ensure the agency that has published the data should be reliable.
(2) Suitability For The Purpose Of Enquiry
  • The Investigator must ensure that the data are suitable for the purpose of the present enquiry.
  • The suitability of the data is determined by investigating the nature, objectives, time of collection etc. of the secondary data.
(3) Adequacy And Accuracy To Avoid Impact Of Bias
  • It is necessary to use adequate data to avoid biases and prejudices leading to incorrect conclusions.
(4) Method Of Collecting Data Used
  • The investigator should also ascertain as to what method was used in collecting the data.
  • Sampling method may be biased depending upon the mode of selection of samples.
  • All these should be ascertained before making use of the secondary data.

The above-mentioned concept is for CBSE class 11 Statistics for What are the Sources of Data. For solutions and study materials for class 11 Statistics, visit BYJU’S or download the app for more information and the best learning experience.