# Collection of Data Notes, Class 11 Economics | SwaVid Collection of Data, NCERT Class 11 Economics: notes with key ideas, definitions, common mistakes and 3 quick checks with worked answers. Canonical: https://www.swavid.com/cbse/class-11/economics/chapter/collection-of-data Source: https://www.swavid.com/cbse/class-11/economics/chapter/collection-of-data # Collection of Data ## Definitions, formats and formulas ## Key ideas ## Common mistakes ## Quick checks ## Keep going ## Questions parents ask ## Class 11 Economics on SwaVid ### Sources of data ### Methods of collecting primary data ### Pilot survey and questionnaire design ### Census versus sample survey ### Sampling techniques ### Statistical errors ### Important secondary data agencies ### Next chapter ### Related chapter ### Related chapter ### All chapters SwaVid › CBSE › Class 11 › Economics › Collection of Data Notes written by SwaVid from the NCERT textbook. Class 11 Economics, Chapter 2. Key ideas, definitions and common mistakes. CBSE does not print marks for a single chapter. Short answer. This chapter explains the sources and methods used to gather statistical information for economic analysis. It highlights the differences between primary and secondary data, survey techniques, census versus sampling methods, and common errors in data collection. Source: NCERT Statistics for Economics (Reprint 2026-27) , Chapter 2, Collection of Data Data can be collected from primary sources where an investigator gathers original information first-hand, or secondary sources where data already gathered by another agency is used. Primary data is collected through personal interviews, mailing questionnaires, or telephone interviews. Each method involves trade-offs between cost, reach, response rate, and the risk of bias. A good questionnaire contains a limited number of clear, unbiased, and logically arranged questions. A pre-test or pilot survey is conducted on a small group to identify ambiguities and test feasibility. A census covers every single element in the population, which requires large resources. A sample survey studies a representative subgroup of the population to draw valid conclusions at lower cost and in less time. Random sampling gives every unit of the population an equal chance of being selected, either by lottery or random number tables. Non-random sampling relies on personal judgment, convenience, or quota. Sampling errors occur due to drawing conclusions from a sample instead of the entire population and decrease with larger sample sizes. Non-sampling errors arise from measurement faults, non-response, recording mistakes, or interviewer bias. In India, major public sources of secondary data include the Census of India, which provides comprehensive demographic details every ten years, and surveys conducted by the National Sample Survey Organisation (NSSO). Try each question first. Then tap it to see the answer. Total number of households in the population N = 50 Each household has an equal chance on the first draw Probability = 1 / N = 1 / 50 = 0.02 0.02 Sample estimate = Rs 15,200 True population parameter = Rs 15,000 Sampling error = Sample estimate - Population parameter Sampling error = 15,200 - 15,000 = 200 Rs 200 Total population N = 400 Sample fraction = 10% = 10 / 100 = 0.10 Sample size = 400 × 0.10 = 40 households 40 households Organisation of Data . Introduction . Presentation of Data . The 13 chapters of Class 11 Economics . CBSE does not give marks to one chapter. It prints marks for units or parts, and the chapter list page shows them all. No. They are written by SwaVid from the NCERT textbook. The CBSE curriculum is the reference for what is assessed. Organisation of Data. SwaVid is an AI tutor for Indian students in Classes 6 to 12. It finds the earlier ideas a child missed, then teaches today’s chapter. Start free to see how it works. - Ch 2 NCERT book - 80 marks, theory paper - 3 quick checks - Treating primary and secondary data as absolute properties of the data itself . Data is primary for the person who collects it first-hand, but becomes secondary when used by any other researcher. - Assuming that sampling errors occur in a complete census . Sampling errors occur only when studying a sample. A complete census has zero sampling error, but non-sampling errors can still occur. - Believing that increasing the sample size eliminates non-sampling errors . Increasing sample size reduces sampling error, but non-sampling error can remain unchanged or even increase as administrative operations grow larger. ## Key Links - [CBSE](https://www.swavid.com/cbse) - [Class 11](https://www.swavid.com/cbse/class-11) - [Economics](https://www.swavid.com/cbse/class-11/economics/chapters) - [Start free →](https://www.swavid.com/signup) - [All 13 chapters](https://www.swavid.com/cbse/class-11/economics/chapters) - [NCERT Statistics for Economics (Reprint 2026-27)](https://ncert.nic.in/textbook.php) - [Open notes](https://www.swavid.com/cbse/class-11/economics/chapter/organisation-of-data) - [Open notes](https://www.swavid.com/cbse/class-11/economics/chapter/statistics-introduction) - [Open notes](https://www.swavid.com/cbse/class-11/economics/chapter/presentation-of-data) - [Class 11 Economics](https://www.swavid.com/cbse/class-11/economics/chapters) - [Start free →](https://www.swavid.com/signup)