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Purposive sampling

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❶For instance, strategies placing greater emphasis on breadth and variation such as maximum variation, extreme case, confirming and disconfirming case sampling are better suited for an examination of differences, while strategies placing greater emphasis on depth and similarity such as homogeneous, snowball, and typical case sampling are better suited for an examination of commonalities or similarities, even though both types of sampling strategies include a focus on both differences and similarities.

Principles of Purposeful Sampling

Purposive sampling
Part 1: What Is Purposive Sampling?
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For example, participants in Homogenous Sampling would be similar in terms of ages, cultures, jobs or life experiences. The idea is to focus on this precise similarity and how it relates to the topic being researched.

For example, if you were researching long-term side effects of working with asbestos, for a Homogenous Sampling, you would only select people who had worked with asbestos for 20 years or longer. Candidates are generally chosen based on their likelihood of behaving like everyone else. For example, if you were researching the reactions of 9 th grade students to a job placement program, you would select classes from similar socio-economic regions, as opposed to selecting a class from an a poorer inner city school, another from a mid-west farming community, and another from an affluent private school.

The polar opposite of Typical Case Sampling, Extreme or Deviant Case Sampling is designed to focus on individuals that are unusual or atypical.

An example would be a study into heart surgery patients who recovered significantly faster or slower than average. Researchers would be looking for variations in these cases to explain why their recoveries were atypical. On occasion, it may be that leaving out certain cases from your sampling would be as if you had an incomplete puzzle - with obvious pieces missing.

In this instance, the best sampling method to use is Total Population Sampling. TPS is a technique where the entire population that meet your criteria e. Total Population Sampling is more commonly used where the number of cases being investigated is relatively small. As indicated by the name, Expert Sampling calls for experts in a particular field to be the subjects of your purposive sampling.

This sort of sampling is useful when your research is expected to take a long time before it provides conclusive results or where there is currently a lack of observational evidence.

Expert sampling is a positive tool to use when investigating new areas of research, to garner whether or not further study would be worth the effort. These categories are provided only for additional information for EPSY students. Patton has proposed the following cases of purposive sampling. Purposive sampling is popular in qualitative research. Qualitative evaluation and research methods 2nd ed.

Maximum Variation — Purposefully picking a wide range of variation on dimensions of interest…documents unique or diverse variations that have emerged in adapting to different conditions. Identifies important common patterns that cut across variations. Homogeneous — Focuses, reduces variation, simplifies analysis, facilitates group interviewing. Typical Case — Illustrates or highlights what is typical, normal, average.

This method is popular with newspapers and magazines which want to make a particular point. This is also true for marketing researchers who are seeking support for their product. They typically start with people in the street, first approaching only 'likely suspects' and then starting with questions that reject people who do not suit. Purposive sampling is non-probability and hence can be subject to bias and error. Snowball sampling , Modal instance sampling.

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Introduction

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Purposive sampling (also known as judgment, selective or subjective sampling) is a sampling technique in which researcher relies on his or her own judgment when choosing members of population to participate in the study.

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One of the major benefits of purposive sampling is the wide range of sampling techniques that can be used across such qualitative research designs; purposive sampling techniques that range from homogeneous sampling through to critical case sampling, expert sampling, and more.

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Explore the research methods terrain, read definitions of key terminology, and discover content relevant to your research methods journey. Purposive sampling is popular in qualitative research. Extreme or Deviant Case – Learning from highly unusual manifestations of the phenomenon of interest, such as outstanding success/notable failures, top of the class/dropouts, exotic events, crises.

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Purposeful sampling is widely used in qualitative research for the identification and selection of information-rich cases related to the phenomenon of interest. Although there are several different purposeful sampling strategies, criterion sampling appears to be used most commonly in implementation. Purposive sampling starts with a purpose in mind and the sample is thus selected to include people of interest and exclude those who do not suit the purpose. This method is popular with newspapers and magazines which want to make a particular point.