Judgment Sampling

Judgment Sampling in research methodology is a statistical method where researchers choose samples (or participants) based on their judgment about who could prove most useful or knowledgeable for the study. The idea is to rely on personal judgment to gather information relevant to research criteria or questions.

This method aims to save time by selecting the right participants or samples from the total population based on judgment instead of applying random sampling. It is a non-probability sampling technique. Since researchers are susceptible to certain behaviors like bias, a researcher’s judgment may not always be right. This methodology is particularly useful in cases where specific groups are relevant to research or knowledge-oriented participants are needed.

• Judgment sampling, or purposive sampling, is a statistical tool where researchers select certain samples based on their judgment and expertise.
• This sampling method saves time as the selection involves only a few participants based on a researcher’s interest. Hence, wrong selection can lead to misleading results.
• As part of qualitative research, this sampling technique is used in pilot studies that require a few samples out of the total population available for study.
• Harboring a bias during sample selection is the most prominent disadvantage of this sampling technique, as researchers may be vulnerable to working with personal beliefs and ideas.

The judgment sampling method allows users to select samples or participants based on their judgment. It is a type of non-random sampling, meaning researchers do not randomly select samples. It is also called purposive sampling. This sampling technique facilitates exploratory research. It also allows researchers to focus on specific groups and populations, particularly if gathering information through people’s knowledge or expertise is the objective of research.

Certain factors can influence the effectiveness of this sampling method. It includes the researcher's expertise, knowledge, sample size, bias, and population interest. If the researcher does not understand the sample population or topic requirements well, they might select the wrong samples. This may lead to false or misleading results.

Judgment sampling techniques are typically not suitable for large sample sizes. Hence, a researcher should consider all sampling techniques to select the right method of data collection. Let us understand this in greater detail using audit as an example.

Auditors use judgment sampling for audits as it proves cost-effective and efficient. The chosen sample will have standard characteristics. The variation in such samples will likely be reliable. Through judgment sampling techniques, auditors may choose certain transactions as samples to check for accounting accuracy, material misstatements, and other audit risks. Based on these samples, they will declare the outcome. Hence, the results of such research cannot be applied to every entity. It cannot be generalized since only a few samples were selected and studied.

The judgment sampling method involves certain steps. Let us study them:

• Defining the population interest: Researchers should understand the group and their interests before selecting specific populations as samples.
• Selecting the sample size and criterion: The sample size is usually small to enable researchers to select populations with the maximum knowledge about the subject in question. For example, if users want to know about an event, they might choose some people with specific characteristics instead of interviewing everyone at the event.
• Analyzing the data: Once the data is collected, researchers analyze it and conclude the process. 

In this section, let us study some examples to understand the varied applications of this sampling technique.

Example #1

Suppose Shelly, a professor at SparkBright University, is researching the opportunities and problems that first-generation students encounter during their years at the university. By first-generation students, Shelly intends to cover all those students whose parents did not secure university-level education.

For this, she selects a sample from a specific target population—students whose parents never went to college. To gather the right students per her sample choice, Shelly contacts various departments and student organizations in the university. She also sends emails to invite people to participate. Finally, Shelly gathered a group of 300 students for the study.

She gathers all the details about these students, including their previous educational background, current economic status, academic successes they have achieved so far, their living arrangements, etc. She interviews them and asks them to fill out independent surveys, too.

Through her focused efforts, Shelly obtained information in line with her research objectives. In this case, the judgment sampling technique helped Shelly get the right data for her study.

Example #2

For a 2023 study titled “Perspectives of French adolescents with ADHD and child and adolescent psychiatrists regarding methylphenidate use”, researchers applied a purposive sampling technique. They focused on deriving qualitative results related to Attention Deficit Hyperactivity Disorder (ADHD) and methylphenidate treatment. Two groups were primarily studied for this: Child and Adolescent Psychiatrists (CAPs) and Adolescents with ADHD.

From the above illustration, we can see that the researchers needed specialized findings from their research activity. Hence, they chose a specific group to ensure specificity and relevance in data collection. In this case, purposive sampling was likely the most suitable choice of sampling.  

Though this sampling method is quite useful in certain cases, it brings both advantages and disadvantages.

Here are some advantages of purposive sampling:

• It saves cost and time since very few samples are involved in the research process.
• Researchers target populations with specific interests to ensure relevance with respect to their research question and objectives.
• It offers variations, with varied opinions, ideas, and perspectives being explored within a single sample.
• With careful sample population selection, errors can be reduced, and highly refined questionnaires and surveys can be created.
• This sampling strategy facilitates exploratory research and enables the gathering of qualitative data through focus groups.

Given below are some disadvantages.

• Bias is a key concern when applying purposive sampling, where a researcher’s beliefs and notions might influence their selection decisions.
• When samples or participants are randomly selected, the possibility exists that more knowledgeable or experienced participants may be excluded.
• Since this method is largely non-representative because researchers are highly selective about which participants they select, generalization is not possible.
• If a researcher's expertise and knowledge fall short, the research activity can generate false results.
• Data confidentiality can be a major concern in certain cases, especially those involving medical reports, personal beliefs, income details, etc.

Both judgment and convenience sampling are sampling methods, and they have distinct characteristics. Listed in the table below are the differences between them.

This has been a guide to what is Judgment Sampling. Here, we explain its examples, advantages, disadvantages, and comparison with convenience sampling. You can learn more about it from the following articles – 

• Sampling Theory
• Sampling Frame
• Jackknife Resampling