Programme: Master of Library & Information Science
Course: MLIS-09: Research Methodology
Target group: Master's students & Research Scholars
NON
PROBABLITY SAMPLING METHODS
Programme: Master of Library & Information Science
Course: MLIS-09: Research Methodology
Target group: Master's students & Research Scholars
1. Purposive Sampling:
Purposive sampling is also called
Judgment sampling. When the researcher deliberately selects certain units for
study from the universe, it is known as purposive sampling. Care must be taken
in the selection of the sample to make it representative of the universe. This
method is more economical and less time consuming. It ensures proper
representation of a cross-section of various strata of the universe if the
researcher has good knowledge about the composition of the universe. Sample
error cannot be calculated in this method.
2. Quota Sampling:
Quota sampling is a special type of
stratified sampling. In this method, first the population is stratified using
some characteristic. Then the number of units to be selected from each stratum
is decided in advance. This number is known as quota which may be based on
characteristics like – age, sex, occupation, income group etc. The choice of
the items from the quota is left to the choice of the researcher.
This
method is convenient to use and economical. This method suffers the
disadvantages of both stratified and purposive sampling. As the sample is not
selected at random, it is not possible to calculate the sampling error.
3. Convenience Sampling:
This method is known as
unsystematic or accidental sampling. In this method, the sample is selected
according to the convenience of the researcher. This convenience may be with
respect to availability of data, accessibility of the units etc. This method
may be used in cases where the universe is not clearly defined; sampling units
are not clear and when a complete source list is not available.
Activity
1. If you want to conduct a survey on those who buy vegetables in the nearby sunday market, which sampling method do you use? List out the reasons.