Page 168 - Data Science class 11
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Disadvantages
        Following are the disadvantages of cluster sampling:

           • Samples  are  biased: This sampling technique is susceptible to biases. Incase clusters representing the entire
          population were formed with preconceived notions or prejudice, it is obvious that outcomes associated with the
          whole population would be biased too.

           • Not always applicable: Cluster sampling requires people to be classified as a unit instead of an individual. This is a
          major drawback with this sampling technique.
        Purposive Sampling

        Purposive sampling is a type of non-probability sampling in which researchers depend on their own judgement
        when selecting participating members of the population in their surveys. It is also known as judgmental, selective, or
        subjective sampling.
        This strategy is used when a researcher suspects that some respondents may be well informed than others, and
        requires an expert to use their judgment in selecting cases with that aim in mind. Purposive sampling may also be
        used with both qualitative and quantitative research techniques. However, this sampling method is widely used in
        qualitative research to identify and select information-rich cases based on the phenomenon of interest.
        It is most effective when studying a specific cultural domain with experts within. Purposive sampling is an acceptable
        sampling method in some specific situations. It uses the judgement of an expert in choosing cases. Purposive sampling
        is often used when a difficult-to-reach population needs to be sampled.

        Advantages

        Following are the advantages of purposive sampling:
           • Cost Effective:  the researcher selects the best-fit participants for the systematic investigation as per his understanding.
          This also saves time.

           • Precise research results: Since the researcher collects qualitative responses, it leads to better insights and more
          accurate research results. Since the researcher gathers information from the best-fit participants, the results are not
          out of context. As such it also lowers the chances of any error.
           • Proper representation: This technique of sampling ensures proper representation of the population when the survey
          has full knowledge of its composition and is free from any prejudice or bias.

        Disadvantages
        Following are the disadvantages of purposive sampling:

           • Not suitable for large samples: This method is unsuitable for the large samples where the size of both the population
          and the sample being studies is large enough.
           • Prone to bias: In purposive sampling, a sample is created initially and this depends on the judgement of the researcher.
          When the judgements are ill-conceived, then this problem becomes a huge disadvantage that can effect result. This
          can only be minimised when there is elicitation, accepted criteria, or a theoretical framework in place.

        What is the best sampling method for qualitative research?

        The two most popular sampling techniques are purposeful and convenience sampling because they align the best
        across nearly all qualitative research designs. Sampling techniques can be used in conjunction with one another very
        easily or can be used alone within a qualitative dissertation.




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