Purposive sampling is a type of non-random sampling technique. In purposive sampling, the researcher deliberately chooses a sample that is most likely to provide information that will answer the research question. This type of sampling technique is often used in qualitative research, as it allows the researcher to select participants who have first-hand experience of the phenomenon being studied.
While purposive sampling can be an effective way to collect data, it is important to note that this method does not produce a representative sample of the population. As such, findings from purposive samples cannot be generalized to the wider population.
Purposive Sampling Methods
There are six types of Purposive Sampling Methods:
- Maximum variation (or heterogeneous) sampling
- Homogeneous sampling
- Typical case sampling
- Extreme (or deviant) case sampling
- Critical case sampling
- Expert sampling
Maximum variation sampling
In maximum variation sampling, a researcher attempts to capture the maximum amount of variation within a population. This is done by selecting a sample that represents the different subgroups within the population. For example, if a population consisted of 50% men and 50% women, the researcher would want to select a sample that was also 50% men and 50% women.
Homogeneous sampling is a process of selecting a sample that is representative of the population. This process is used in many different fields, such as market research and opinion polling.
Typical case sampling
Typical case sampling is a method of selecting a sample from a population in which the researcher deliberately chooses subjects that are representative of the population as a whole. This type of sampling is often used in qualitative research, as it allows the researcher to gain an in-depth understanding of a particular phenomenon.
Extreme case sampling
Extreme case sampling is a method used to study atypical cases that are both rare and representative of a larger population. This type of sampling is often used in studies of deviant behavior or exceptional individuals.
Critical case sampling
Critical case sampling is a method of qualitative data collection that involves selecting a limited number of cases that are critically important to the research question. This method is often used in exploratory studies when the researcher is seeking to generate new hypotheses or understand a phenomenon.
Expert sampling is a type of purposive sampling in which participants are chosen because they have knowledge about a particular phenomenon or experience.
This type of sampling is often used when researchers are investigating a new or understudied phenomenon and want to gain insights from those with first-hand knowledge. It can also be used to triangulate data from other sources, such as documents or public records.
Example of Purposive Sampling
An example of purposive sampling would be: Choosing a sample of people to interview who are all victims of domestic abuse. This type of sampling is often used in qualitative research, as it allows the researcher to gather in-depth information from individuals who have first-hand experience of the phenomenon being studied.
Another example of purposive sampling would be: if a researcher was looking for participants who had experience with a certain type of event or circumstance. In this case, the researcher would not randomly select participants from a population, but would instead hand-pick individuals who have the specific knowledge or experience that the researcher is looking for.
When to use Purposive Sampling
This type of sampling is often used when researchers are interested in studying a particular group of people, and it is not possible to study the entire population. While purposive sampling does not provide a representative sample, it can still be useful for generating new ideas and insights.
When deciding whether or not to use purposive sampling, researchers should consider the purpose of the study and the research question. If the goal is to generate new theories or ideas, then purposive sampling may be appropriate. However, if the goal is to test hypotheses or make generalizations about a population, then other types of sampling (e.g., probability) would be more appropriate.
Purpose of Purposive Sampling
This non-random method is used when the researcher wants to study a specific population or target a specific type of information.
Purposive sampling is often used in qualitative research, as it allows the researcher to select participants based on characteristics that are important to the study. For example, if a researcher is interested in studying how parents of teenagers experience stress, she may use purposive sampling to select parents of teenagers who live in a certain area or come from a certain background.
While this method is not as scientific as other methods, such as random sampling, it can be useful in obtaining the specific data that the researcher is looking for.
Advantages of Purposive Sampling
There are some advantages of purposive sampling:
- It allows researchers to target specific groups that may be difficult to reach through other means.
- Purposive sampling can be used to ensure that the sample represents a diversity of perspectives.
- It allows the researcher to target specific individuals who have unique skills or perspectives that may be useful for the research project.
- This method can be used to recruit participants who are difficult to find through other sampling methods.
Disadvantages of Purposive Sampling
Some Disadvantages of Purposive Sampling are:
- It can lead to selection bias because the researcher is choosing who to include in the study.
- This can distort the results because not everyone has an equal chance of being selected.
- It can be difficult to generalize the findings to a larger population because the sample is not randomly selected from all potential participants.