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Collection of Data - Class 11 - Statistics
- 2. Synopsis 1. Key terms 2. Sources of data 3. Surveys 4. Census or complete Enumeration 5. Sample survey 6. Questionnaire 7. Types of questions 8. Open ended Vs Close ended 9. Mode of data collection 10. Pilot survey 11. Methods of sampling 12. Important agencies
- 3. Key Terms Variable: The values which change, such as production of food grains per annum, temperature of a city, etc. They are represented by the letters X,Y or Z. Observation: The value of an variable. Data: Observations corresponding to different variables. Statistical Investigation: It means search for information conducted by using statistical methods.
- 4. Key Terms Investigators: The person who conducts statistical investigation. Enumerators: A person who helps investigator in the collection of data. Respondents: The persons from whom statistical information is collected. Statistical Unit: The items on which measurements are taken. Example; weight in kgs.
- 5. Population or the Universe: it means totality of the items under study. Sample: It refers to a group or section of the population from which information is to be obtained. Good sample: It is smaller than the population and is capable of providing accurate information about the population at lower cost and lesser time. Key Terms
- 6. Sources of Data 1. Primary Data: when the enumerator collect the data by conducting an enquiry or an investigation. They are based on first hand information. For example, you will have to enquire from a large number of school students, by asking questions from them to collect the desired information. 2. Secondary Data: When the data have been collected and processed by some other agency. It is based on second hand information. For example, information obtained from publish sources such as government reports, newspaper.
- 7. Surveys Survey is a method of gathering information from individuals. The surveys are done to describe some characteristics like price, quality, usefulness and popularity, etc. The purpose is to collect data. On the basis of area covered there are two methods of survey: 1. Census Survey 2. Sample Survey
- 8. Census or Complete Enumeration A survey which includes every element of the population. It covers every individual unit in the entire population. The example includes Census of India, which is carried out every ten years. This surveys are carried for demographic data on birth, death, literacy. Advantages Disadvantages Results are absolutely correct, accurate and reliable A lot of time, energy and money is required to collect data Less chances of biasness Suitable for certain specific cases Data related to each element is collected Large number of enumerators are required for collecting data
- 9. Sample Survey In this a sample from the population is surveyed. The first step is selecting a sample to identify the population. Than select Representative Sample, as it is difficult to study entire population. Example: Population, research, etc. Advantages Disadvantages Economical as only some units are studied Partial investigation of the universe Not time consuming Not easy to select a sample which represent whole population Less efforts are required as small portion is studied It is complicated process and difficult
- 10. Questionnaire The most common type of instrument used in surveys for collecting primary data is questionnaire. While preparing the same the following points are kept in mind: • It should not be too long • The series of questions should move from general to specific • The questions should be precise and clear • The questions should not be ambiguous • The question should not use double negatives • The question should not be a leading question • The question should not indicate alternatives to the answer
- 11. Types of Questions in Questionnaire 1. Closed ended or structured questions: It could be a two-way question or a multiple choice question. When there are only 2 possible answers it is called a two way question. When there is a possibility of more than 2 answers it is called multiple choice question. 2. Open ended or unstructured questions: It could be descriptive types. When a person gets a chance to talk more about any topic.
- 12. Differentiate Close Ended Versus Open Ended Closed Ended Question Open Ended Question Easier to compare responses Detailed and qualifies responses Quicker and easier answers Unlimited possible answers Easy to interpret Difficult to interpret Easy to score Difficult to score Easy to codify for analysis Difficult to codify for analysis Example: Do you smoke? Example: What is your view about globalization?
- 13. Mode of Data Collection 1. Personal Interviews: In this method, The investigator conducts interviews with the respondents and obtained required information. Two types of interview are: • Direct Personal Interview: Investigator conducts face to face interview with respondent. • Indirect Personal Interview: Data is collected by interviewing third person who are directly or indirectly concerned with the subject matter of enquiry, they are witness to the situation.
- 14. Personal Interviews Advantages Disadvantages High degree of originality Costly and time consuming Information is reliable Cannot be used where area of study is large Easy to administer Highly prone to personal biasness Elastic method as necessary adjustments in the set of questions can be made It requires that the investigator is skilled and trained
- 15. Mode of Data Collection 2. Telephone Interviews: In this method, the investigator asks questions over the telephone. Advantages Disadvantages Cheaper and takes shorter time Obstruct visual reactions. They allow researcher to assist respondents by clarifying questions Excludes the population who are not having telephone connection. Helpful where respondents are reluctant to answer questions in personal interview.
- 16. Mode of Data Collection 3. Mailing Questionnaire: In this method, the required data are collected by mail. The questionnaire is sent to each respondent by mail with a request to complete and return it by a given date. Advantages Disadvantages Less expensive Possibility of misunderstanding the questions Allows access to researchers in remote areas. Produces low response rate Allows respondents to take sufficient time to answers Data are not reliable
- 17. Mode of Data Collection
- 18. Pilot Survey/ Pre- Testing It is a trial survey which helps to test the effectiveness of the questionnaire on a small group. Importance: 1. it helps in pre-testing of the questionnaire, so as to know the shortcomings and drawbacks of the questions. 2. It also helps in accessing the suitability of questions, clarity of instructions, performance of enumerators and cost and time involved.
- 19. Methods Of Sampling 1. Random Sampling: Method where samples are selected at random. In this method, every individual unit has an equal chance of being selected. Methods under random sampling: a) Lottery Method: In this method all the items in the populations are assigned a distinct number and these are written on identical piece of paper and put in a bowl. Samples are selected on random. b) Table of Random Numbers: In this random numbers are arranged in rows and column which are selected on population size. c) Exit Polls: it is used to predict election results. In this technique a random sample of voters, who exit from the polling booths are asked who they voted for.
- 20. 2. Non-Random Sampling: In this all the units of the population do not have an equal chance of being selected. Methods under this are: a) Judgement/Purposive/Deliberate Sampling: Here sample units are selected consciously by the investigator on the basis of his judgement. This method is subject to personal bias of investigator. b) Quota Sampling: Here the investigator is allotted definite quota and he is required to collect the required data from a specific numbers of unit of each quota. c) Convenience Sampling: Here the investigator collects the sample units on the basis of his convenience. Methods Of Sampling
- 21. Sampling and Non Sampling Errors Error in statistics is used to denote the difference between the true value and the estimated value. Errors can be classified as: 1. Sampling Errors: the difference between the actual value of a parameter of the population( which is not known) and its estimate( known). It is possible to reduce sampling error by increasing the size of the sample. 2. Non- Sampling Errors: It includes: • Errors in Data Acquisition: From recording incorrect response • Non-Response: It occurs when interviewer is unable to contact person listed in the sample • Sampling Bias: It occurs when in a sampling plan some members of target population could not included
- 22. Important Agencies of Secondary Data 1.Census of India: It provides the most important and complete demographic record of population. These are conducted every 10 years. The census official collects information on various aspects of population such as sex ratio, literacy, migration, etc. Which are used to interpret and analyse to understand many economic and social issues in India and accordingly plans and policies are formulated.
- 23. 2.National Sample Survey Organisation: it was established in 1950 under the Ministry of Finance to conduct surveys and collect data on estimates of literacy, school enrolments, maternity, PDS, etc to publish surveys through reports. NSSO conducts continuous surveys on various problems in successive rounds. Important Agencies of Secondary Data
- 24. Thank You! Lesson by Anjali Kaur Suri TGT Maths, PGT Economics M.A. Economics, M.Com (Finance), PGD Banking & Finance, B.A. Hons (Economics), B.Ed (Maths & SST), NISM, NSDL and IELTS certified. For enquiries or topic suggestions, email: contact@geniusedu.co.in Connect on Linkedin: www.linkedin.com/in/anjali-kaur