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Unformatted text preview: p with greater accuracy of results.
4. It has greater scope.
5. It has greater adaptability.
6. If the population is too large, or hypothetical or
destroyable sampling is the only method to be used.
The limitations of sampling are given below:
1. Sampling is to be done by qualified and experienced
persons. Otherwise, the information will be unbelievable.
2. Sample method may give the extreme values sometimes
instead of the mixed values.
3. There is the possibility of sampling errors. Census survey is
free from sampling error.
Types of Sampling:
The technique of selecting a sample is of fundamental
importance in sampling theory and it depends upon the nature of
investigation. The sampling procedures which are commonly used
may be classified as
1. Probability sampling.
2. Non-probability sampling.
3. Mixed sampling.
2.4.1 Probability sampling (Random sampling):
A probability sample is one where the selection of units
from the population is made according to known probabilities. (eg.)
Simple random sample, probability proportional to sample size etc.
15 2.4.2 Non-Probability sampling:
It is the one where discretion is used to select
‘ representative’ units from the population (or) to infer that a sample
is ‘ representative’ of the population. This method is called
judgement or purposive sampling. This method is mainly used for
opinion surveys; A common type of judgement sample used in
surveys is quota sample. This method is not used in general
because of prejudice and bias of the enumerator. However if the
enumerator is experienced and expert, this method may yield
valuable results. For example, in the market research survey of the
performance of their new car, the sample was all new car
2.4.3 Mixed Sampling:
Here samples are selected partly according to some
probability and partly according to a fixed sampling rule; they are
termed as mixed samples and the technique of selecting such
samples is known as mixed sampling.
Methods of selection of samples:
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This note was uploaded on 01/18/2014 for the course BUS 100 taught by Professor Moshiri during the Winter '08 term at UC Riverside.
- Winter '08