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Census vs sampling

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Census vs sampling

  1. 1. CENSUS VS SAMPLING PROBABILITY & NON -PROABILITY SAMPLING SAMPLING & NON -SAMPLING ERROR PRESENTED BY: DHIRESH CHAWLA SUNIL CHICHRA VIVEK PANDEY
  2. 2. WHEN DATA IS TO BE COLLECTED FROM EACH MEMBER OF THE POPULATION, IT IS KNOWN AS CENSUS SURVEY WHEN DATA IS TO BE COLLECTED ONLY FROM SOME MEMBERS OF THE POPULATION, IT IS KNOWN AS SAMPLE SURVEY
  3. 3.  Sampling Method Advantage over Census Method  Speed : Less Time  Economy : Less Expensive  Adaptability  Scientific Approach : More Dependable, Less Manpower, Less Administrative Control  Census Method Advantage over Sampling Method  Gives Exact & Accurate results
  4. 4.  Sampling used in infinite cases while Census can’t measure or studied Ex : Inspection of Bombs Test on Quality of Apples In those Census Destroyed all itself  Census were Complete Enumeration while Sampling were Partial Enumeration
  5. 5. Pros n Cons Of CENSUS Method • • • True Measure Benchmark data obtained for future studies Detailed information for sub-groups Higher costs Long time to collect & process • Difficult to enumerate • •
  6. 6. Pros n Cons of SAMPLING Method  Low Cost  Less Time  Representative Average results  Not representative total population  Not suitable for producing benchmark data
  7. 7. Probability Sampling  Also known as Random Sampling  Randomly selection of samples  In this probability can be accurately determined  Includes :  Simple Random Sampling  Systematic Random Sampling 2nd sample are taken at Interval  Stratified Random Sampling Relevant subgroups created
  8. 8. Simple Systematic Stratified
  9. 9. Non-Probability Sampling  Also known as Non-Random Sampling  Selection is non-random & probability of their selection cannot be determined  Includes :  Convenience Sampling Based on ease of access  Purposive Sampling Based on what researcher think  Quota Sampling Based by defined quotas  Volunteer Sampling Internet based opinion survey
  10. 10. Advantages & Disadvantage Probability Sampling  Reliable  Easy estimation of errors  Costly to select  Need skilled Manpower  Sample may not provide required data in some cases
  11. 11. Advantages & Disadvantages Non- Probability Sampling  Easy & cheap to select  Data easily obtained  Understood easily  Sampling errors can’t estimated  Variability Can’t Measured or controlled
  12. 12. Sampling Error Error caused by the act of taking a sample They cause sample results to be different from the results of census Differences between the sample and the population that exist only because of the observations that happened to be selected for the sample Statistical Errors are sample error
  13. 13.  Causes :     Faulty Selection Of Sample Substitution Faulty Demarcation of sampling units Two types of error 1. Biased error 2. Unbiased error
  14. 14. Non - Sampling Errors  Arises from other types of errors than from a sample Ex: Tabulation errors  Occur at every stage at the planning or execution of census or sample survey  Also Call as Systematic Error  Not controlled by sample size
  15. 15.  Arises From : Lack of Trained & experienced Investigators  Errors committed during presentation  Duplication of units  Defective frames & faulty selection of samples units  Lack of adequate inspection & supervision of primary staff  Errors in data processing operation like as coding, tabulation etc. 

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