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This page provides complete NCERT exercise solutions for CBSE Class 11 Economics Chapter 2 — Collection of Data. Review the Key Concepts first, then work through the intext questions and chapter-end exercises. For numerical or practical questions, the step-by-step approach is shown. Use these solutions to cross-check your answers and prepare thoroughly for exams.
Key Concepts (Quick Recap)
- Primary Data: collected by the investigator for the first time; original, reliable, expensive
- Secondary Data: already collected by someone else; not original, less reliable, cheaper
- Methods of Collecting Primary Data: (a) Direct Personal Investigation, (b) Indirect Oral Investigation, (c) Information from Correspondents, (d) Mailed Questionnaire, (e) Enumeration
- Sources of Secondary Data: Published (government reports, journals, committee reports) and Unpublished (company records, research institutions)
- Census Method: every item of the population is surveyed; accurate but costly
- Sample Method: a representative part of the population is surveyed; economical but less accurate
- Random Sampling: every unit has an equal chance; types — simple random, stratified, systematic, multi-stage
- Non-Random Sampling: selection depends on judgement; types — judgement, quota, convenience, purposive
- Sampling Errors: difference between sample result and population result; decreases with larger samples
- Non-Sampling Errors: errors in data collection, processing, or interpretation; can occur even in census
- Questionnaire Design: questions should be simple, clear, not leading, logically arranged, and not too many
Intext Questions
Section 2.1 — Sources of Data
Section 2.2 — Sampling Methods
Chapter-End Exercise
Question 1
Frame at least four appropriate multiple-choice options for the following question: Which of the following is a method of collecting primary data?
(a) Direct Personal Investigation (b) Indirect Oral Investigation (c) Published Government Reports (d) Mailed Questionnaire
The correct options are (a), (b), and (d). Option (c) is a source of secondary data, not primary data.
Question 2
Frame at least four appropriate multiple-choice options for the following question: Which of the following is a source of secondary data?
(a) Census of India (b) National Sample Survey Reports (c) Questionnaire filled by respondents (d) RBI Bulletin
The correct options are (a), (b), and (d). Option (c) yields primary data.
Question 3
Which of the following is a method of random sampling?
(a) Judgement sampling (b) Quota sampling (c) Stratified sampling (d) Convenience sampling
Question 4
Distinguish between census and sample methods of data collection.
| Basis | Census Method | Sample Method |
|---|---|---|
| Coverage | Every unit of population is studied | Only a part of population is studied |
| Cost | Very expensive | Economical |
| Time | Time-consuming | Quick |
| Accuracy | More accurate | Less accurate (subject to sampling error) |
| Suitability | Small population | Large population |
| Example | Population Census of India | National Sample Survey |
Question 5
Distinguish between sampling and non-sampling errors.
| Basis | Sampling Errors | Non-Sampling Errors |
|---|---|---|
| Cause | Arise because only a part of population is studied | Arise due to mistakes in data collection, processing or analysis |
| Occurrence | Only in sample method | Can occur in both census and sample |
| Control | Can be reduced by increasing sample size | Can be minimised by proper training, supervision |
| Nature | Random | Systematic or random |
| Example | Sample mean differs from population mean | Recording errors, non-response, bias |
Question 6
Explain the merits and demerits of the direct personal investigation method.
Merits: 1. Information is original and reliable as the investigator collects it personally. 2. The investigator can clarify doubts and get accurate responses. 3. Information can be collected according to the specific needs of the study. 4. The investigator can observe the body language and sincerity of the respondent.
Demerits: 1. Very expensive and time-consuming, especially for large areas. 2. Personal bias of the investigator may affect the data. 3. The investigator needs to be trained and skilled. 4. Not suitable for covering a wide geographical area. 5. Respondents may not give truthful answers in the presence of the investigator.
Question 7
What are the precautions to be taken while drafting a questionnaire?
1. Questions should be simple, clear, and easy to understand. 2. Questions should not be ambiguous or leading. 3. The number of questions should be reasonable — not too many. 4. Questions should be logically arranged — from general to specific. 5. Personal and sensitive questions should be avoided or placed at the end. 6. Multiple-choice or closed-ended questions are preferred for ease of analysis. 7. Questions should be relevant to the objective of the study. 8. The questionnaire should begin with a brief introduction explaining the purpose. 9. A covering letter assuring confidentiality should be attached. 10. The questionnaire should be pre-tested (pilot study) before actual use.
Question 8
Explain random sampling and its types.
Types of Random Sampling:
1. Simple Random Sampling: Every unit has an equal and independent chance. Selection can be through lottery method or random number tables.
2. Stratified Random Sampling: The population is divided into homogeneous groups (strata) based on a characteristic, and then random samples are drawn from each stratum proportionally.
3. Systematic Sampling: Units are selected at fixed intervals from a list. For example, every 10th unit from a list of 1000 units.
4. Multi-Stage Sampling: Sampling is done in stages. First, large groups are sampled, then sub-groups within them, and so on. Used in large-scale surveys like the NSSO.
Question 9
Explain non-random sampling and its types.
Types of Non-Random Sampling:
1. Judgement Sampling: The investigator uses their judgement to select the sample. Used when a specialised group needs to be studied.
2. Quota Sampling: The investigator selects a fixed number (quota) from each group. Widely used in market research and opinion polls.
3. Convenience Sampling: The sample is selected on the basis of convenience and accessibility. Quick but less reliable.
4. Purposive Sampling: Units are selected with a specific purpose in mind. Used for qualitative research.
Question 10
What do you mean by sampling errors? How can they be reduced?
How to reduce sampling errors: 1. Increase the sample size — larger samples are more representative. 2. Use random sampling methods — they reduce bias in selection. 3. Use stratified sampling when the population is heterogeneous. 4. Ensure the sampling frame (list of population units) is complete and up-to-date.
Question 11
What are non-sampling errors? Give examples.
Types and examples: 1. Errors in data collection: Incorrect recording, misunderstanding of questions, non-response by respondents. 2. Errors in data processing: Mistakes in coding, tabulation, or calculation. 3. Errors in data analysis: Wrong method of analysis, misinterpretation of results. 4. Investigator bias: The investigator influences the responses or selects data selectively. 5. Respondent bias: Respondents deliberately give wrong answers (e.g., understating income). 6. Non-response: Some selected units refuse to respond or are unavailable.
Question 12
Explain the mailed questionnaire method. What are its merits and demerits?
Merits: 1. Most economical method for covering a large area. 2. Saves time as the investigator does not visit each respondent. 3. Respondents can fill the questionnaire at their convenience. 4. Suitable for sensitive topics as it ensures privacy. 5. No investigator bias as the investigator does not interact directly.
Demerits: 1. Low response rate — many questionnaires may not be returned. 2. Respondents may not understand the questions properly. 3. Incomplete or careless responses are common. 4. No guarantee that the right person fills the questionnaire. 5. Follow-up is difficult and expensive.
Question 13
What is indirect oral investigation? When is it used?
When to use: 1. When the subject is sensitive (e.g., alcoholism, drug addiction) and direct questions would yield false answers. 2. When the respondent is unwilling or unable to provide information. 3. When the investigator needs supplementary information to verify direct responses.
Question 14
Explain the importance of pilot survey.
1. It reveals whether the questions are clear and understood by respondents. 2. It helps estimate the time and cost required for the main survey. 3. It identifies problems in the questionnaire (ambiguous questions, sensitive questions). 4. It helps determine the appropriate sample size. 5. It provides an opportunity to modify and improve the questionnaire.
Question 15
List the published sources of secondary data in India.
1. Census of India — population data every 10 years 2. National Sample Survey Organisation (NSSO) — socio-economic surveys 3. Economic Survey of India — annual economic data 4. RBI Bulletin — banking and monetary data 5. Statistical Abstract of India — compiled by CSO 6. India Year Book — general statistical reference 7. Reports of commissions and committees — on specific topics 8. International publications — UN, World Bank, IMF reports 9. Research journals and periodicals — subject-specific data 10. State government publications — state-level statistical handbooks
Internal Links
- [Chapter 2 Guide — Collection of Data](/school/cbse/class/11/economics/cbse-collection-of-data)
- [All Class 11 Economics Solutions](/school/cbse/class/11/economics/solutions)
- [Class 11 Economics Subject Guide](/school/cbse/class/11/economics)