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CHAPTER 2, COLLECTION OF DATA, Collection :It is the process of collecting data or information from different sources.A place from data obtained is called, data source.Statistical data can be obtained from two sources .The are primary and secondary sources., Distinguish between primary and secondary data, PRIMARY DATA, SECONDARY DATA, It is first hand in use., , It is second hand in use., , It is collected from an enquiry., , It is collected from published sources., , It is in the form of raw materials., , It is in the form of finished products., , What are the qualities of a good questionnaire?, The main qualities of a good questionnaire are the following., •, •, •, •, •, •, •, , Questionnaire should not be too long., A series of questions should move from general to specific., The questions should not be ambiguous. They should enable the respondents to answer quickly,correctly, and clearly., The questions should not use double negatives., The questions should not be a leading question,which gives a clue about how to answer., The questions should be precise and clear., The questionnaire should include both open ended and closed ended questions., , MODE OR METHODS OF DATA COLLECTION, There are three basic of collecting primary data. The are the following, 1) Personal interview:this method is used when the researcher has to access all the members. The main merits, and demerits of the method are the following., ADVANTAGES, DISADVANTAGES, Highest response rate, Most expensive, Allows all types of questions, More time taking, Better for using open ended questions., Possibility of influencing respondents, Allows clarifications to ambiguous questions, 2) Mailing questionnaire: The data in a survey are collected by mail,such method of databases collection is, called mailing questionnaire. It’s advantages and disadvantages are as follows., ADVANTAGES, DISADVANTAGES, Least expensive, , Cannot be used by illiterates, , Only method to reach remote areas, No influence on respondents, Maintains anonymity of respondents, , Long response time, Does not allow clarifications to ambiguous questions, Reactions can’t be watched, , Best for sensitive questions, , 3) Telephone interview: In a telephone interview,the investigator asks questions over the telephone. It’s, advantages and disadvantages are as follows.

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ADVANTAGES, , DISADVANTAGES, , Relatively low cost, , Limited use, , Relatively less influence on respondents, , Reactions can’t be watched, , Relatively high response rate, , Possibility of influencing the respondents, , PILOT SURVEY, ., , When the questionnaire is ready ,it is advisable to conduct a try out with a small group of, Population is known as pilot survey or pre testing of the questionnaire. It’s advantages, , Are the following, •, •, •, •, , It help us to access the suitability of the questionnaire., It help us to identify the drawbacks and shortcomings of the questionnaire., It help us to calculate survey cost and time, It help us to pre testing of the questionnaire., , CENSUS OR COMPLETE ENUMERATION: A survey which includes every element of population is called census, of complete enumeration.In India census are conducted by Registrar General Of India(R.G.I.).ln India census ,which, carried out every ten years. Last census of India was held in the year 2011.According to the 2011 census ‘India’s, population is 121crores.The main advantages and disadvantages of census are the following., ADVANTAGES, DISADVANTAGES, Additional information is to be obtained, More time taking, More reliable information obtained, More expensive, Covers the entire population, More enumerators needed, • SAMPLE SURVEY: Data or information is collected from samples only, such, method of data collection is called sample survey.A sample refers to a group or section, of population from which information is to be obtained. A good sample is generally, smaller than population and give reasonably accurate information about the, population. In India sample surveys are conducted by NSSO.Most of the surveys are, sample surveys because of the following reasons., i., It provides reasonably reliable and accurate, information., ii. It needed lower cost and shorter time, iii., More detailed information can be collected, iv., Smaller team of enumerators is needed, According to the selection of samples .sample survey divided into two. They are the following., 1) RANDOM SAMPLING: In the random sampling every individual has an equal chance, of being selected as a sample.The individuals who are selected are just like the ones who, are not selected.In random sampling ,samples are selected with the help of random, number tables or Lott’s so this method is also called lottery method., 2) NON RANDOM SAMPLING.:In non random sampling all the unit of the population do, not have an equal chance of being selected as sample.The convenience or judgement of, the investigator plays an important role in the selection of the sample., SAMPLING ERRORS: The difference between the actual value of parameter of the population and it’s estimate is the, sampling error.lt is possible to reduce the magnitude of sampling error by taking a larger sample.

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NON SAMPLING ERRORS:Non sampling errors errors are more serious than sampling errors because sampling error, can be minimised by taking larger sample. It is difficult to minimise non sampling errors, even taking a large sample.some, of the non sampling errors are:, • Errors in data acquisition:This type of error arises from recording of incorrect responses., • Non response errors: It occurs if an interviewer is unable to contact a person listed in the sample ., • Sampling bias:Sampling bias occurs when the investigator performs biased in the selection of samples., List out some data collecting agencies in India., •, •, •, •, •, , Central statistical organisation. (CSO), National sample survey organisation.(NSSO), Registrar general of India(RGI), Directorate general of commercial intelligence and statistics(DGCIS), Labour bureau., , Previous questions., 1), 2), 3), 4), 5), , Most of the surveys in India are sample surveys why?, (March 2017), Enumerate the different types of sampling?, (September 2016), Prepare a table shows the differences between census survey and sample survey., ( March 2016), ............ are the main sources of data. A) primary B) secondary c) both A and B D) none of these (do), Distinguish between primary and secondary data., , (March 2015) State whether the following statements are true or false., 1) There are many sources of data., 2) Telephone interview is the most suitable method of collecting data ,when the population is literate and spread, over a large area., 3) Data collected by investigator is called the secondary data., 4) Non sampling errors can be minimized by taking large samples., 5) There is certain bias involved in the non random selection of samples., , PREPARED BY, RAJESH.S, K.T.C.T.E.M.H.S.S KADUVAYIL, THIRUVANANTHAPURAM