Under What Conditions Would It Be Appropriate to Use a Snowball Sampling Technique?

Sampling and methods of data collection in qualitative research

Professor, College of Nursing, CMC, Vellore, Bharat

Date of Web Publication

9-Jun-2020

Correspondence Accost:

Source of Support: None, Conflict of Interest: None

Qualitative research deals with data collected in narrative form which requires an in-depth knowledge in selecting advisable sampling techniques and data collection methods. Unlike quantitative studies, non- probability sampling techniques are used in qualitative studies to enhance data richness. Sample size is not adamant using statistical formula, merely is based on the principle of data saturation and the type of qualitative written report methodology. Qualitative studies adopt flexible data drove plans which may evolve as the study progresses. Observation, in-depth interviews and focus group discussions are the primary data collection methods in qualitative studies.

Keywords: qualitative methods, purposive sampling, snowball sampling, theoretical sampling, sample size, observation, in-depth interview, focus groups.

How to cite this commodity:
Seetharaman B. Sampling and methods of data collection in qualitative research. Indian J Cont Nsg Edn 2016;17:41-seven

Introduction

In nursing, the ii widely used approaches to carry out studies in pedagogy, service, and assistants are quantitative and qualitative in nature. The steps in doing inquiry with these 2 approaches are different from each other in terms of sequence and methodology. By and large, researchers believe that the data collection in qualitative approach is quite exhaustive and fourth dimension consuming compared to the quantitative arroyo. Due to this reason, researchers may not exist inclined to prefer qualitative methods. Still, qualitative studies play a vital office in generating new concepts and developing nursing theories (Polit & Beck, 2014). This article discusses the various sampling techniques and data collection methods adopted in qualitative studies.

Sampling in Qualitative Enquiry

The main goal of qualitative research is to understand a phenomenon, not to represent a population or make generalizations from report samples to population. The participants are selected using non- probability sampling techniques which will allow the researchers to select people who volition give a wealth of information (Polit & Brook, 2014).

Types of Qualitative Sampling

The non random sampling techniques used in qualitative studies are classified below:

1. Volunteer sampling
2. Snowball sampling
3. Purposive sampling
4. Theoretical sampling

A. Volunteer Sampling

Volunteer sampling is i method of convenience sampling where the researcher posts a request for volunteers who had the experience being studied or who can talk virtually the phenomenon of interest, to participate in the report. Volunteer sampling is helpful when the study topic or the experience is hard to identify through routine survey or when the study topic is sensitive in nature. For example, if a researcher wants to explore the experiences of women with urge incontinence, volunteer sampling method will exist a good choice. Although this approach is like shooting fish in a barrel and economical, it is not a preferred method e'er, because of the fear that the volunteers may not be those who tin provide sufficient information (Burns & Grove, 2004; Polit & Brook, 2014).

B. Snowball or Concatenation Sampling

In snowfall brawl sampling, study participants recommend others who take the same experiences or accept similar characteristics which are of interest to the researcher (Burns & Groove, 2005). The early on sample members are asked to refer others who run across the eligibility criteria. This method is more toll-constructive compared to convenience sampling. However, this strategy can cause ethical problems if the study deals with personal or sensitive areas such as sexuality, drug utilise and then on because confidential information nearly participants is revealed to the researcher before getting their consent (Polit & Beck, 2014). [Figure 1] depicts graphically, the result of i snowball sample. The outset participant aged 27years, from United kingdom who referred the researcher to the 2d person from Italy and goes on.

C. Purposive or Purposeful Sampling

Information technology refers to selecting participants who will most benefit the study. Information technology as well involves inviting participants who can give the nigh information on the experience that is studied. A broad assortment of purposive sampling methods are described by Patton (2001) and Patton (2002).

i. Criterion Sampling

Criterion sampling involves selecting people who run into some predetermined criterion of importance to the study. This sampling tin be used following a survey study if the researcher wants an in- depth analysis from the detail participants identified, e.1000., A researcher wants to explore patients' satisfaction with nursing care. If the level of satisfaction is assessed using a 5point Likert calibration with 1 = 'not at all satisfied' and 5 = 'extremely satisfied' a criterion that may exist used for qualitative sampling is: "Interview with patients who score simply 1 and ii".

ii. Maximum variation sampling

This strategy involves cases representing variations on specified aspects of a phenomenon of interest east.g. geographical variations, education etc. This type of sampling helps in capturing and describing central themes that cut beyond variation (common patterns among variations) resulting in high quality, detailed description of each example, e.chiliad., Evaluating the essential newborn care programme in districts of India. Sample could be mothers with children less than v years. Participants demand to exist purposefully selected representing geographical variations eastward.g. sites in rural, urban, semi-urban areas.

iii. Extreme or Deviant Case Sampling

This sampling method is sometimes called equally outlier sampling. It includes selection of participants who give data which is very different from the bulk of others (unusual or special in some way) or at either terminate of a continuum instead of selecting typical cases or a randomly selected 1, east.g., outstanding successes andnotable failures.

four. Homogeneous Sampling

This method includes pick of similar cases to describe a particular grouping in-depth. Information technology is often used in focus grouping discussions, e.g., Selecting participants who have like demographic characteristics such as age, gender, education, etc.

v. Critical Case Sampling

Critical cases are "information rich" participants (Patton, 2002) who tin can make great impact on the development of noesis. When such participants are purposively included as samples it is called equally Critical Case Sampling.

D. Theoretical Sampling

According to Patton (2002), theoretical or theory- based sampling is defined every bit "a strategy involving the option of incidents, slices of life, fourth dimension periods or people on the basis of their potential manifestation or representation of important theoretical constructs." This sampling is used in grounded theory enquiry. It is based on the question, 'Who will provide the data that volition assist in the development of theory that is evolving?' (Glaser, 1978). The data tin can exist nerveless from any private or grouping by the researcher which tin can be used equally a relevant source of data for theory generation.

Sample Size in Qualitative Research

Unlike quantitative studies, the sample size is not mathematically calculated in qualitative studies. In that location are no set rules for deciding on the sample number in qualitative studies (Patton, 2002). Yet, 1 must continue in heed that the sample should be large plenty to make meaningful comparisons in relation to the research questions. The guiding principle used is 'information saturation' (Polit & Beck, 2014). Itmeans, sampling to the point at which the researcher recognizes no new information is obtained from the participants and data on all dimensions of an emerging category is generated (Glaser, 1978). In qualitative research, sampling method and sample size may vary and change as the study progresses and findings evolve.

Sample size also varies based on the Qualitative traditions chosen for the study. In Ethnography in that location is no restriction on number of samples. Phenomenologists who look at lived experiences of people choose less than 10 participants who have experienced the phenomenon. In grounded theory studies 20 to 30 individuals may be included just equally data saturation is specifically emphasized the number may vary accordingly (Polit & Beck, 2014).

Data Collection in Qualitative Research

In that location are three main information collection methods in qualitative inquiry. They are observation, in-depth interview and focus group give-and-take. These methods differ with respect to the relationship betwixt the data collector and the participant (Rossman&Rallis, 1998).

1. Observation methods

Observation method involves observing and recording what is seen. This method is used non merely in qualitative but as well in quantitative enquiry. Observation is also office of the interview and group word as the researchers also observe the body linguistic communication, facial expression and other nonverbal cues while being an interviewer or the moderator for group discussions. The qualitative observations will differ from quantitative approach primarily in the focus on process rather than numbers. The types of ascertainment are discussed below:

a. Participant Ascertainment

As the proper noun implies, the researcher volition participate in terms of interaction with participants and their activities. "Participant observation is the process of enabling researchers to learn nigh the activities of the people nether written report in the natural setting through observing and participating in those activities" (DeWalt & DeWalt, 2002). Participant observation requires a prolonged flow of engagement with the participants in the report in their social and cultural context(Patton, 2002). This method of information collection is used extensively in Ethnography research.

To illustrate this procedure imagine that a researcher wants to written report virtually intendance giving experiences of spouses of mentally sick patients. The researcher after getting an informed consent may have to spend the initial days in establishing relationship with the family and and then keep observing the care giving activities that are meaningfully related to the experience. The researcher continues to dialogue with the spouses as observations are carried out.

b. Mystery Client Technique

It is a special type of participant observation which may combine quantitative and qualitative data collection and is used in patient-provider studies. This method is used when the situations that are likely to make alterations with respect to the participants' behaviour in the presence of observer. Participants/patients are trained to enact roles which will reverberate their real-life experiences and they will nowadays themselves to actual health intendance providers in the natural setting. They tape their experience on a structured course and study their observations to researchers later on each encounter. The cardinal feature of this method is that the provider is not aware of the patients' real identity. The conclusion to apply this method needs to be taken just after careful reflection on the purpose of the study and ethical implications linked to this, considering getting an informed consent is an result (Ulin, Robinson & Tolley, 2004). For example, this method can be adopted to study on interactions between patients and health intendance providers.

c. Non-participant or Non-reactive Observation

In this, the researcher collects data without interacting or reacting visibly to participant's activeness. The researcher observes events equally unobtrusively as possible as an outsider. For instance, the researcher may desire to study the admission process of a woman in pain getting admitted into the labour room. The researcher observes the patient's experience including the interaction betwixt the participants and health care providers without participating in the event.

The quality of the not- participant observation information relies on the power of the researchers to watch diligently and mind without interrupting the natural menstruation of action. The distortion of observed behaviour must exist kept at minimum. For this, the observer needs to be introduced to the participants as someone who will learn about the health care provided in that setting. This will farther let the observer to remain with participants and observe silently from the periphery while providing intendance. The longer the observation menstruum, the more effective will be the observation equally the participants get accepted to the presence of the observer.

Taking notes on the observation made is very important, and based on the notes the listing of things or events to be observed will exist revised at the terminate of each observation period. Note taking needs to be done as unobtrusively every bit possible because frantic scribbling of verbatim conversations and flipping notebook pages volition notify participants that they are existence observed which will eventually increase their anxiety. It is mandatory that the researcher summarises the notes, and incorporates the mental notes immediately afterwards each observation period. Interpretations or tentative conclusions need to be drawn to the notes which will enable the researchers to formulate or add together new points to be observed in the subsequent sessions (Ulin et al., 2004).

d. Documentary Research

It is a blazon of non-reactive ascertainment method. In this method, the material which is examined has been already collected and reported by others for other purposes. However, it gives a lot of information about how people think and acquit in natural settings with no outsider influence. The examples of documentary sources are hospital and clinic records, newspaper stories, radio and television shows etc. Qualitative researchers also use this method for secondary analysis of transcriptions from interviews or focus group discussion conducted in the past (Ulin et al., 2004).

Ways to Recording Observations

Participant observers are expected to participate, detect and tape the observations. Information through observation cannot exist trusted to memory. The observer needs to record information as shortly equally possible subsequently the observation (Polit & Beck, 2014). The normally used observational records are logs or field diary and field notes.

i) Logs or Field Diary

Log is a record to exist used in the field to annotation the daily events and conversations. This tin also be used for planning and making time schedule and for keeping rail of expenses.

ii) Field notes

The researcher must have a practice of recording chat and events once happened without any delay and besides to set aside time for making field notes. Each note must start with the date, time, location, purpose of ascertainment and the demographic data of participants beingness observed. After making the field notes, the researcher needs to develop working hypothesis, plan subsequent steps, revisit and revise the notes. As the observations are beingness recorded, the researcher should keep request new questions, interpreting and reinterpreting the information he or she had heard and seen. Summaries of the transcriptions need to exist entered into the notes if audiotape is used for collecting the data. When the book of field notes increases, the researcher should go on organising the notes (Ulin et al., 2004).

There are two types of field notes, one is descriptive notes and the other is reflective notes. Descriptive notes will include objective descriptions of observed events and conversations, dialogue and context. Reflective notes are used to document researcher'south personal experiences, reflections and progress while in the field (Polit & Beck, 2014).

Advantages and Disadvantages of Observation Method

The ascertainment method provides deeper and richer understanding of situations pertaining to man behaviors, hence used widely by researchers whose interest is to develop conceptualization of phenomena. The potential problems associated with ascertainment are observer bias and observer influence (Polit & Beck, 2014).

two. In-depth Interviews

In in-depth interview method, the researcher/ interviewer is guided past a few wide topics. These interviews are basically an exchange between the 1 interviewer and one respondent. Information technology is otherwise known equally "conversational partnership" (Rubin & Rubin, 1995), a "social encounter" (Holstein and Gubrium, 1999) and conversation with a purpose (Burgess, 1984). The participants will be constantly encouraged to have an agile part in discussions. The main goal or focus of this method is to collect information-rich information which calls for mental sharpness, sensitivity and practice of the researcher (Ulin et al., 2004).

How to frame Qualitative Questions in in-depth interview?

The questions demand to be breezy, non-judgemental, and open. The interviewer must speak clearly but casually and avert any suggestions. The qualitative interviews contain of three types of questions namely primary questions, follow-upwardly questions and probes (Rubin & Rubin, 1995).

The main questions must come from the themes and subthemes of the study topic. The questions should move from easy and to the lowest degree threatening to more than complex and interesting issues. The near important questions will be asked from diverse angles and at unlike points in time. The follow-up questions will move the discussions into a deeper level. At this point, the participant understands that the interviewer is interested to heed to him and gather more data. A probe is also like to follow-up questions which will further take the discussions into next level. There must be a residual between too much and too niggling information. Probing, when insufficient will lead to boredom, but when aggressive leads to intrusion (Rubin & Rubin, 1995).

For case in a study on parenting children with burns (Ravindran, Rempel & Ogilvie, 2013) the researcher started with the chief question which was general question on the phenomenon: Tin can you tell me about your child's burn injury?.

The follow up question included questions such as how they managed the wound at habitation and the probe was by asking what they meant by proverb it was hard. Probes are primarily used to get rich and in-depth responses which will bring along implicit meanings related to an experience (Patton, 2002).

Stages of In-depth Interview

Rubin and Rubin (1995) described the following stages of in-depth interview in sequence:

1. Creating natural involvement: The researcher will begin the interview by starting an informal chat with the participants in gild to set up the stage for the conducive environment. Informed consent volition be obtained later explaining about all the details of the report including the introduction of the researcher.

2. Encouraging conversational competence: The interview will start with piece of cake and non-threatening questions which will let the participants to feel secure and enable them to requite data freely. The researcher should use the language in which participants find it like shooting fish in a barrel to share their experiences as a partner rather than an interviewer.

3. Showing understanding: The researcher will encourage the participants to requite more in-depth details by letting them know that he or she understands and feels empathetic with the responses of the participants. The main focus is to put the participants at ease so equally to let them to share their experiences without fear.

4. Getting facts and basic description: As the conversation between the researcher (partner) and the participants progresses, the researcher slowly gets into the heart of the interview. During this stage, the participants volition be asked to describe an incident with respect to the topic.

v. Request difficult questions: One time the researcher is certain of the trusting relationship with participants, he tin ask the participants regarding nearly difficult questions. The difficult questions can be repeated at different time points also which will offering opportunities for the participants to respond from various angles. Before asking the difficult questions, the researcher can remind the participants of the fact that the interview data will be kept confidential.

6. Toning down the emotional level: The researcher must assistance in restoring the sense of privacy among the participants particularly if the conversation is on sensitive bug. The researcher will ask the participants whether they want to ask anything to the researcher.

vii. Endmost while maintaining contact:At the terminate of the interview conversation, the participants will be thanked for spending their time and sharing their valuable experiences. The investigator volition too reiterate on confidentiality of the record. Although the interview is over, the informal conversations between the researcher and the participants may continue.

These steps are very critical to be followed while collecting qualitative data using the in-depth interview.

Strengths and Limitations of In-depth Interviews

The strengths and weaknesses of Qualitative Interviewing is elaborated by Holloway (2005). In interviews, participants' own words are captured and the researcher is also able to clarify any doubts immediately. Researchers are also able to get extensive data on the concept that is emerging past asking additional probing questions either in the same interview or in the subsequent interviews. Nonverbal behaviours too may be observed and noted.

The major limitation of interviews is that they are time consuming. Another vital bespeak to be noted is that the narration is a reconstruction of facts rather than the actual behaviour. Interference from noise and other people in the area where the interviews happen also can accept an adverse effect on the quality of data.

3. Focus Groups/ Group Discussion

Morgan (1988), defines focus group equally "apply of grouping interaction to produce data and insights that would be less attainable without the interaction plant in a group." Focus groups depend on exchange of ideas amongst participants to specific questions asked past the interviewer.

Like in-depth interviews, in this method also, three types of questions are used to collect information: the principal questions, follow-up questions and probe questions. Focus groups will be effective in giving rich information over other methods peculiarly when the researcher wants to do report about topics apropos social norms, expectations, values and beliefs. As far equally the size and limerick of the focus groups is concerned, it is imperative to include participants with similar characteristics with respect to the study topic. For instance, if the topic is on coping of mothers who had nonetheless births, participants need to have the experience of having had a however birth (Ulin et al., 2004).

Recruitment of appropriate number of participants for a focus group is withal another important gene in qualitative studies. Each group must have at least vi to ten participants to enhance or facilitate the flow of discussion efficiently by the members and to manage the grouping by the moderator. Anonymity of the participants is important which will encourage them to speak without inhibition ( Morgan, 1995).

The number of focus groups required depends upon the number of defining demographic variables. For each variable, two focus groups can exist conducted. In a day, one grouping with 2-hour word including transcription can be managed which will exist of around 25 to twoscore pages of transcript (Ulin et al., 2004).

Process to Bear Focus Groups

• The moderator welcomes the participants and introduces herself or himself and the annotation taker and so explains about the part of each and the purposes of focus group.
• The moderator assures participants that anonymity and confidentiality of information shared will be maintained.
• Informed consent will exist obtained.
• The ground rules to be followed during the focus groups will be explained to the participants e.g., speaking one at a time, not interrupting each other.
• The participants are encouraged to speak freely.
• The first topic volition be introduced slowly.
• The moderator must exist in a position to create a group of conversational partners and he/she should have proficient interpersonal skills.
• The moderator should accept proficient listening skills to listen to the conversation amongst participants carefully and non-judgementally while all the same keeping the discussion moving and focused. Audio recording or videotaping of discussions will ensure authentic data.
• At that place should be ii moderators for efficient focus groups, out of whom, ane will guide the discussion and the other will monitor the recording and note taking.
• The moderator asks the participants to summarise the points what they shared or the moderator himself can summarize in order to analyze problems before ending the word.
• The participants are given chance to make sure that the shared data has been understood correctly and recorded accurately.
• A feedback from participants may be collected if preferred.

Autonomously from all the steps mentioned higher up, the researcher should see that brief background information about the participants is collected to assistance the researcher to describe the participants, interpret what the participants have said, and evaluate the emerging themes. The background information should be relevant and brief and to be kept confidentially with coding (Basch, 1987; Ulin et al., 2004)

Advantages and Limitations of Focus Grouping Interviews

Focus group interviews are toll- effective and need less fourth dimension to generate information as many participants' views on a single topic tin can be gathered in a few meetings. As participants interact within the grouping the quality and richness of data is enhanced. Further, differences and similarities in participants' views can be immediately assessed every bit the interview is conducted. Participants may also feel motivated by the interactions. It provides real life data including cultural beliefs (Patton, 2002; Manoranjitham, 2007).

The major drawback is the need for expertise in conducting the focus group discussions effectively. If the researcher is not skilful enough to moderate the give-and-take and keep the conversation flowing, in-depth information may not exist generated and therefore time volition be wasted. Each private may not get adequate time to express all their views every bit every participant should be given fourth dimension to share their own. Keeping confidentiality can be difficult and sensitive issues may not be discussed openly. Participants may neglect to appear for the interviews and if enough number of participants are not available a focus group interview may not be possible (Patton, 2002). The researcher sometimes may directly become into the topic without really checking about the involvement of the participants (Kitzinger, 1995).

Decision

There are some similarities with regard to sampling techniques used among qualitative traditions such equally use of pocket-size sample size, and non-random sampling. However, sampling may vary depending upon the written report methodology. The researchers' knowledge and experience play a major office in determining the sample size. Data collection strategies in qualitative enquiry are flexible in nature. Qualitative researchers should focus on the quality information rather than quantity. Developing and maintaining a trustworthy relationships with participants is essential in qualitative data generation.

Conflicts of Interest: The author has alleged no conflicts of involvement.

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