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Convenience sampling (also known as grab sampling, accidental sampling, or opportunity sampling) is a type of non-probability sampling that involves the sample being drawn from that part of the population that is close to hand. That is, a sample population selected because it is readily available and convenient, as researchers are drawing on relationships or networks to which they have easy access. The researcher using such a sample cannot scientifically make generalizations about the total population from this sample because it would not be representative enough. For example, if the interviewer was to conduct such a survey at a shopping center early in the morning on a given day, the people that he/she could interview would be limited to those given there at that given time, which would not represent the views of other members of society in such an area, if the survey was to be conducted at different times of day and several times per week. Another common example occurs with paid focus groups designed to study consumer responses to new or changed products. Only those people with the free time and inclination to participate are studied. In addition, these groups may also exhibit constrained financial circumstances that see them value participating in these studies as a worthwhile use of their time. These groups may not be representative of the target market of consumers for the product. An example might be a paid focus group surveying consumer sentiments towards an expensive watch. Those who elect to participate in the study may be of a demographic highly unlikely to ever buy an expensive watch. While it is convenient to use this paid focus group to study the sentiment towards the expensive watch, the results are unlikely to be representative of potential customers for the watch itself. This type of sampling is most useful for pilot testing. Credibility of a researcher's results by convenience sampling will depend on convincing the reader that the sample chosen equates to a large degree of the population from which they are drawn.
A convenience sample is a type of non-probability sampling method where the sample is taken from a group of people easy to contact or to reach. For example, standing at a mall or a grocery store and asking people to answer questions would be an example of a convenience sample. This type of sampling is also known as grab sampling or availability sampling. There are no other criteria to the sampling method except that people be available and willing to participate. In addition, this type of sampling method does not require that a simple random sample is generated, since the only criteria is whether the participants agree to participate
Convenience sampling is not often recommended for research due to the possibility of sampling error and lack of presentation of population. But it can be handy depending on the situation. In some situations, convenience sampling is the only possible option. For example, a college student who is doing a term project and wants to know the average consumption of beer in that college town on Friday night. He will most probably call some of his friends and ask them how many cans of beer they drink or will go to a nearby party to do an easy survey. There is always a trade-off between this method of quick sampling and accuracy. Collected sample may not represent the population of interest and therefore, be a source of bias.
In the example above, if college town has small population mostly consists with students and that particular student chooses a graduation party for survey; then his sample has fair chance to represent the population. Larger sample size will reduce the chance of occurring sampling error.
Another example, a gaming company wants to know how one of their games is doing in market after a day of its release. So their analyst creates an online survey on Facebook to rate that game. The major challenge of his approach will be reaching to the people who play games. As social media is a vast place, it's always difficult to collect samples from population of interest. Most of the general people may not be interested or will not take seriously while filling up the survey which results sampling error. The best possible way can be if the analyst creates and posts that poll to fan page dedicated to game-lovers. He may find lots of people in that group who are interested to judge and rate the game critically.
Convenience sampling can be used by almost anyone and has been around for generations. One of the reasons that it is most often used is due to the numerous advantages it provides. This method is extremely speedy, easy, readily available, and cost effective, causing it to be an attractive option to most researchers.
Expedited data collection
When time is of the essence, many researchers turn to convenience sampling for data collection, as they can swiftly gather data and begin their calculations. It is useful in time sensitive research because very little preparation is needed to use convenience sampling for data collection. It is also useful when researchers need to conduct pilot data collection in order to gain a quick understanding of certain trends or to develop hypotheses for future research. By rapidly gathering information, researchers and scientists can isolate growing trends, or extrapolate generalized information from local public opinion.
Ease of research
For researchers who are not looking for an accurate sampling, they can simply collect their information and move on to other aspects of their study. This type of sampling can be done by simply creating a questionnaire and distributing it to their targeted group. Through this method, researchers can easily finish collecting their data in a matter of hours, free from worrying about whether it is an accurate representation of the population. This allows for a great ease of research, letting researchers focus on analyzing the data rather than interviewing and carefully selecting each participant.
Since most convenience sampling is collected with the populations on hand, the data is readily available for the researcher to collect. They do not typically have to travel great distances to collect the data, but simply pull from whatever environment is nearby. Having a sample group readily available is important for meeting quotas quickly, and allows for the researcher to even do multiple studies in an expeditious fashion.
One of the most important aspects of convenience sampling is its cost effectiveness. This method allows for funds to be distributed to other aspects of the project. Oftentimes this method of sampling is used to gain funding for a larger, more thorough research project. In this instance, funds are not yet available for a more complete survey, so a quick selection of the population will be used to demonstrate a need for the completed project.
Even though convenience sampling can be easy to obtain, its disadvantages usually outweigh the advantages. This sampling technique may be more appropriate for one type of study and less for another.
The results of the convenience sampling cannot be generalized to the target population because of the potential bias of the sampling technique due to under-representation of subgroups in the sample in compare to the population of interest. The bias of the cannot be measured. Therefore, inferences based on the convenience sampling should be made only about the sample itself.
Convenience sampling is characterized with insufficient statistical power to identify differences of population subgroups. (Bornstein, et al. 2013)
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