Write a Short Note on Sampling and Non-sampling Error.
Random sampling error occurs because
the particular sample selected/accepted is an imperfect representation of the
population of interest. The errors involved in the collection, processing and
analysis of a data may be broadly classified under the following two heads:
i)
Sampling
Error and
ii)
Non-sampling
Errors.
i)
Sampling Errors:
Sampling error is the variation
between true mean value for the population and the true mean value of the
sample. The error, which arises entirely due to sampling and no other reasons
can be attributed to cause such error, is called sampling error.
In other words, sampling errors arise
due to the fact that only a part of the population (i.e., sample) has been used
to estimate population parameters and draw inferences about the population. As
such the sampling errors are absent in a complete enumeration survey.
Sampling errors are due to the
following reasons:
@ Faulty selection of the sample
@ Substitution
@ Faulty demarcation of sampling units
@ Constant error due to improper choice
of the statistics for estimating the population parameters.
ii)
Non-Sampling Errors:
Non-sampling error can be attributed
to sources other than sampling and they may be random or non-random. Non-sampling
errors can occur at every stage of the planning or execution of census or
sample survey. Non-sampling errors arise from the following factors.
@ Faulty Planning or Definitions
@ Response Errors
o
Response
errors may be accidental
o
Prestige
bias
o
Self-interest
o
Error
due to interviewer
o
Failure
of respondent’s memory
@ Non-response Errors
@ Errors in coverage
@ Compiling errors
@ Publication errors.
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