Page 166 - Data Science class 11
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In  this  type  of  sampling,  the  first  available  primary  data  source  will  be  used  for  the  research  without  additional
        requirements.  In  other  words,  this  sampling  method  involves  getting  participants  wherever  you  can  find  them
        conveniently.
        In probability sampling, each element in the population has a known nonzero chance of being selected through the
        use of a random selection procedure.
        In pilot studies, convenience sample is generally used because it allows the researcher to obtain basic data and trends
        regarding his study without the difficulties of using a randomized sample.
        Convenience sampling technique is applicable to both qualitative and quantitative studies, although it is most
        frequently used in quantitative studies while purposive sampling is often used in qualitative studies.
        This technique of sampling doesn't include random selection of participants. The opposite is probability sampling,
        where participants are randomly selected, and each has an equal chance of being selected.
        Since the generalisability of convenience samples is not much clear, the estimates derived from convenience samples
        are often biased (i.e., sample estimates are not reflective of true effects among the target population because the
        sample doesn't represent the target population precisely).

        Advantages
        Following are the advantages of convenience sampling:
           • Time saving: This method is used to quickly collect data. Since it follows a simple approach to draw sample from that
          part of the population that is easier to find, data collection takes minimal time. Convenience sampling is not just easy
          to use, but also has other research advantages.
           • Convenient to use: This sample is used as the last resort when researchers cannot have an access to the list of all the
          people in a population. It is generally chosen as it is convenient in terms of location, accessibility, etc.
        Disadvantages

        Following are the disadvantages of convenience sampling:
           • Biased: This method of sampling can be very biased as the researchers may be tempted taken in the perspectives or
          responses of only those people they know.
           • Lack of credibility: The results cannot be generalised due to lack of representation of the population. There can be
          sampling errors as well.

        Quota Sampling
        This method is identical with stratified sampling, i.e. the population is divided into groups, based on certain attributes.
        A quota is a type of trade restriction where a government restricts the number or the value of a product that another
        country can import. For example, when a government places a quota restricting another country to import no more
        than 8 tons of grain.
        In production quotas, a government or a group of producers, put a restriction on the supply of a specific product so as
        to maintain its price. For example, the Organisation of Petroleum Exporting Countries (OPEC) sets a production quota
        for crude oil in order to 'maintain' the price of crude oil in world markets. This is a sampling technique that includes
        only certain groups to ensure a fair representation of those groups to avoid oversampling.

        This is necessary for quality upgrading or (downgrading) of the low-quality (high-quality) firm, an increase in average
        quality, and minimising of domestic consumer surplus, irrespective of the quality of production of foreign firm.

        How to Perform Quota Sampling
           • Divide the population into subgroups. These should be exclusive.
           • Figure out the proportion of subgroups to the population.
           • Choose your sample size.
           • Choose participants, being careful to adhere to the subgroup's characteristics.

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