Census vs sampling
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Transcript of Census vs sampling
CENSUS VS SAMPLINGPROBABILITY & NON-PROABILITY
SAMPLINGSAMPLING & NON-SAMPLING
ERROR
PRESENTED BY:DHIRESH CHAWLA
SUNIL CHICHRAVIVEK PANDEY
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
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
Sampling used in infinite cases while Census can’t measure or studiedEx : Inspection of Bombs
Test on Quality of Apples In those Census Destroyed all itself
Census were Complete Enumeration while Sampling were Partial Enumeration
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
Pros n Cons of SAMPLING Method
Low CostLess TimeRepresentative Average results
Not representative total populationNot suitable for producing benchmark data
Probability SamplingAlso known as Random SamplingRandomly selection of samplesIn this probability can be accurately
determinedIncludes :
Simple Random SamplingSystematic Random Sampling
2nd sample are taken at Interval
Stratified Random SamplingRelevant subgroups created
Simple
Systematic
Stratified
Non-Probability Sampling
Also known as Non-Random SamplingSelection is non-random & probability of their
selection cannot be determinedIncludes :
Convenience SamplingBased on ease of access
Purposive SamplingBased on what researcher think
Quota SamplingBased by defined quotas
Volunteer SamplingInternet based opinion survey
Advantages & DisadvantageProbability Sampling
ReliableEasy estimation of errors
Costly to selectNeed skilled Manpower
Sample may not provide required data in some cases
Advantages & DisadvantagesNon- Probability Sampling
Easy & cheap to selectData easily obtainedUnderstood easily
Sampling errors can’t estimatedVariability Can’t Measured or controlled
Sampling Error
Error caused by the act of taking a sampleThey cause sample results to be different from the results of censusDifferences between the sample and the population that exist only because of the observations that happened to be selected for the sampleStatistical Errors are sample error
Causes :
Faulty Selection Of Sample Substitution Faulty Demarcation of sampling units
Two types of error 1. Biased error2. Unbiased error
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
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.