Purposeful Sampling is the most common sampling strategy. In this type of sampling, participants are selected or sought after based on pre-selected criteria based on the research question. For example, the study may be attempting to collect data from lymphoma patients in a particular city or county. The sample size may be predetermined or based on theoretical saturation, which is the point at which the newly collected no longer provides additional insights.
Click on the following link for a desciption of types of purposeful sampling: Types of Purposeful Sampling. Quota Sampling is a sampling technique whereby participant quotas are preset prior to sampling.
Typically, the researcher is attempting to gather data from a certain number of participants that meet certain characteristics that may include things such as age, sex, class, marital status, HIV status, etc.
Click here for more information on this type of sampling: Snowball Sampling is also known as chain referral sampling. In this method, the participants refer the researcher to others who may be able to potentially contribute or participate in the study. This method often helps researchers find and recruit participants that may otherwise be hard to reach.
For more information, click here: Collecting Qualitative Data from highness Qualitative Sampling Methods by ProProfs. Resource Links Qualitative Research Methods - A Data Collectors Field Guide - This comprehensive, detailed guide describes various types of sampling techniques and provides examples of each, as well as pros and cons. Page Options Share Email Link. Collection criteria for the future cannot be planned in advance as the criterion emerges as the theory evolves.
Which groups are included? To study this often multiple comparison groups are used. The groups are chosen based on the theoretical criteria or relevance. Sociologists or researchers often evade the problem by studying only one group and trying to describe the subgroups. Often the differences among the groups or sub groups are just stated but a theoretical analysis is not conducted.
One of the advantages here is that the analyst has the liberty to adjust his control of the data collection, to ensure that the data is relevant to the emerging theory. Also it should be noted that usually groups are chosen only for a single comparison, therefore there is usually no pre-planned or definite set of groups for all the categories.
Another interesting fact is that it is almost impossible to cite the number of groups and the type of groups until the research is completed. One of the major differences with comparative analysis is that comparative analysis focus on the verification and description using accurate evidence.
Why are groups selected? Comparing groups gives the researcher the advantage of development of variety of categories. The main criterion is that the data collected should apply to a particular category or property, irrespective of the differences or similarities. As the researcher compares groups, he gains control over two scales of generality.
Population scope Also differences and similarities can either be maximised or minimised, depending on the type of groups being compared. This gives the researcher more control and helps him discover more categories. This then helps him to develop and relate to more theoretical properties which lead to enhancing the emerging theory.
When the researcher minimises differences among groups, he is able to establish a definite set of conditions under which a category exists. Whereas on maximising, he is able to gather a variety of data with strategic similarities among the groups. Generally in theoretical sampling, the researcher aims at maximising differences as this brings about greater coverage in the variation among different aspects, making the theory more elaborate.
How are the groups selected? The researcher should actively search for data that is theoretically relevant. Rather than focusing on the group, greater focus should be placed on the emerging theory. It should also be noted that larger the contrast between the groups, greater will be the probability of evident comparison between the two. As the research progresses and the researcher studies the same group or different sub-groups, he then arrives at few categories, which on saturation generate his theory.
Initially, theoretical sampling is used only for a pragmatic purpose of generating a theory. The ability to generate an extensive understanding of a completely well theory defined in any field through research takes in the account of theoretical sampling.
It first focuses on the problem area and then into the various approaches that need the basis of grounded theory. For example, how confident men handle prospective marks or how policemen act toward people of African descent or what happens to students in medical school that turns them into doctors, is dependent on the theoretical framework that the researcher arrives with.
As a general methodology, classic grounded theory can use either qualitative or quantitative data Glaser Theoretical sampling in particular has become embroiled within the multiple interpretations of sampling in qualitative research, often being misconstrued as inter-changeable with purposeful sampling Sandelowski In Theoretical Sensitivity Glaser sought to address this same concern, and thirty years later this remains to be a notable problem.
Purposeful sampling is defined as the selection of participants with shared knowledge or experience of the particular phenomena identified by the researcher as a potential area for exploration Sandelowski Typically, to ensure selection of the most information rich participants, the researcher will establish a set of inclusion or exclusion criteria based upon research questions generated deductively from prior knowledge of the area and a preliminary review of related literature.
The concern is with who or what to sample for the purpose of answering questions about a predetermined topic. In contrast, the selection of participants in theoretical sampling, and the reason underpinning that selection, will change in accordance with the theoretical needs of the study at any given time Morse While a purposeful sample is selected at the outset of the study for a predetermined purpose, theoretical sampling progressively and systematically tailors data collection to serve the emergent theory.
Theoretical sampling is thus always purpose-driven; the sample is selected for the purpose of explicating and refining the emerging theory.
It has been clearly established that theoretical sampling is guided by the emerging theory, and is concerned with where to sample next and for what theoretical purpose.
Yet for novice researchers newly embarking upon a grounded theory study, the most pressing practical concern is perhaps where to start. Furthermore, if the purpose of theoretical sampling is to seek data that will contribute to developing categories of the emerging theory, the researcher must surely first have the beginnings of a theory — some tentative ideas — upon which to build.
Evidently there is an unavoidable need to begin somewhere. In this sense theoretical sampling may involve the purposeful selection of an initial starting point before moving into theoretical sampling when data analysis begins to yield theoretical concepts. It is pertinent to remember that the starting point is only that, and the researcher should avoid formulating a preconceived conclusion that these initially sampled characteristics will contribute to theoretical variation Glaser For example, to sample only according to demographic characteristics is to deduce that they will be relevant to the emerging theory Glaser ; Morse However, because points of departure such as demographic characteristics have not emerged from the theory, they must be considered merely another variable awaiting a verdict as to its relevance.
Indeed, descriptive data may be elevated into abstract theory only by way of comparing theoretical categories and properties, not mere demographic opposites Hood Pre-existing knowledge can guide the researcher in identifying a starting point for data collection, but this knowledge should be awarded no relevance until validated or dismissed by the formulation of the emerging theory.
In the same way as ideas must earn a way into the theory, the converse is also true; it is possible that initial ideas will earn a way out. For the novice grounded theorist, the initial concern about where to start is often accompanied by a similar concern regarding the decision to stop data collection. Given the inductive nature of theory generation, it is understood that theoretical sampling, including the point at which sampling will cease, is controlled throughout the study by the emerging theory.
While this definition carries a degree of simplicity, theoretical saturation can be a difficult concept to understand, particularly for first-time grounded theorists who are yet to actually experience reaching the saturation point within a study.
While the qualitative researcher seeks descriptive saturation, the grounded theorist is concerned with saturation at a conceptual level. Theoretical saturation is not mere descriptive redundancy. Instead, theoretical sampling does not aim for full descriptive coverage, but systematically focuses and narrows data collection in the service of theoretical development. In so doing, the grounded theorist is able to transcend the descriptive level typical of qualitative research.
By saturating categories that seem to have the most explanatory power and integrating these into and around a core variable, the grounded theorist is able to present the theoretical essence of a substantive area. While the saturation point indicates theoretical stability whereby the core category accounts for as much variation in the data as possible, it is crucial to understand that these concepts and hypotheses are openly modifiable within the substantive area.
Saturation in classic grounded theory is thus neither concerned with verifying hypotheses or exhausting the description of a particular situation at a particular point in time.
Instead, the researcher should be concerned with generating a theory that can cope with changing situations a particularly important consideration within the ever-changing healthcare arena and less with in-the-moment accuracy that has little temporal transferability.
From a grounded theory perspective, however, there lies an inherent risk in the excessive description of potentially irrelevant detail. This is of particular concern in relation to the above discussion, whereby researchers should not automatically assume the relevance of participants socio-demographic characteristics to the emerging theory.
While demographic or social characteristics may provide a starting point for data collection, by presenting a thick, isolated description of participants at the start of a grounded theory research article the researcher is at risk of either belying an inappropriate approach to sampling, or obscuring the analytic flow and progression of theoretical insights thus compromising the credibility of an otherwise trustworthy study.
Morse has criticised the way in which theoretical samples are presented as static without detailing and justifying the selection and sequencing of the sampling process. Typically, researchers provide a one-off description of participants in the methods section of research articles, and ignore the impact of sampling decisions made during analysis Barbour However, if the researcher does not capture the flow of the theoretical sampling process, the complexities involved in the development of the theory may be lost.
Theoretical sampling is intertwined inextricably with the abstraction of description into theory, and is crucial to discovering and refining categories and their properties and suggesting relationships between concepts. Studies that produce an artificially neat and static account of the grounded theory process serve only to obscure this complexity Barbour Novice grounded theorists should be careful to write-up a grounded theory study in a manner that best reflects the methodology.
Grounded theory researchers should avoid isolated, one-off, static descriptions of participants but should instead be challenged to integrate within their write up the progression, justification and contribution of sampling decisions so as to mirror the complex and iterative process of theory development. Theoretical sampling is theoretically oriented, and will thus be different for every theory.
Theoretical sampling is associated with grounded theory approach based on analytic induction. Theoretical sampling is different from many other sampling methods in a way that rather than being representative of population or testing hypotheses, theoretical sampling is aimed at generating and developing theoretical data. Theoretical sampling .
dierences between purposeful and theoretical sampling for nursing research. Keywords: sampling, qualitative, grounded theory sample size in order to ensure representativeness and INTRODUCTION the qualitative principle of appropriateness that requires Sampling procedures in qualitative research are not so purposeful samplingand a ‘‘good’’ .
In theoretical sampling the researcher manipulates or changes the theory, sampling activities as well as the analysis during the course of the research. Flexibility occurs in this style of sampling when the researchers want to increase the sample size due to new factors that arise during the research. The goal of qualitative research is to provide in-depth understanding and therefore, targets a specific group, type of individual, event or process. To accomplish this goal, qualitative research focus on criterion-based sampling techniques to reach their target group.
Qualitative research is designed to explore the human elements of a given topic, while specific qualitative methods examine how individuals see and experienc Theoretical sampling is a tool that allows the researcher to generate theoretical insights by drawing on comparisons among samples of data. First of all, both theoretical sampling and snowball sampling correspond to what is usually called "sampling strategies" in qualitative research. 1) Theoretical sampling makes up the classical.