There are many ways to interview people, e.g. individually or in focus groups. However, they share some general principles and techniques. Therefore in what follows we address the general principles. After that we present a chapter on individual semi-structured interviews and a chapter on focus groups.
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As with any data collection, interviewing (individually or in focus groups) has to be planned within the overall research approach taking into account the particular aims of the qualitative data collection.
The planning of data collection has to be prepared early in the process of the overall research. Qualitative research is time consuming, on the level of data-collection, data-analysis and reporting. All the steps are presented in the next figure.
Figure 2 – Flowchart: interviewing people

In qualitative research we select people who are likely to provide the most relevant information (Huston 1998). In order to design the sample and cover all variability around the research issue, the researchers must have an idea about the different perspectives that should be represented in the sample. This is called “field mapping” of the key players who have a certain interest in the problem under study. The role of this explicit “field mapping” is often underestimated but essential in order to build a purposive sample. It is possible that this “field map” evolves during the data collection. The notion of “representativeness” here is not understood in the statistical way. The idea of representation is seen as a “representation of perspectives, meanings, opinions and ideas” of different stakeholders in relation to the problem researched and their interest. In order to select the participants for interviews or focus groups, one should ask “do we expect that this person can talk about (represent) the perspectives (meanings given to the situation) of this stakeholder group”. The aim is to maximize the opportunity of producing enough data to answer the research question (Green 2004).
Ideally there should be a mixture of different “population characteristics” to ensure that arguments and ideas of the participants represent the opinions and attitudes of the relevant population. Also the unit of analysis should be taken into account. This could be for example “individuals for their personal opinions/experience/expertise” or “individuals because they represent organizational perspectives”.
Moreover in order to make comparisons within and between types of participants, the sample design should take this already into account. In Table 9, two criteria for comparison, for example age and socio-economic status, are already included to allow comparative analysis between age or status groups.
There is a wide range of sampling approaches (e.g. Miles and Huberman 1994, Patton 2002, Strauss and Corbin 2008). It is not uncommon in qualitative research that the research team continues to make sampling decisions during the process of collecting and analysing data. However, a clear documentation of the sampling criteria is needed when doing qualitative research. These criteria should cover all relevant aspects of the research topic. The researcher should identify the central criteria and translate them in observable sample criteria. In addition, the chosen criteria should leave enough variation to explore the research topic (Mortelmans, 2009). For example, in a research about factors influencing the decision to have or refrain from having a refractive eye surgery in the two last years, sampling criteria were:
In what follows we describe a number of sampling strategies. All the sampling strategies are non-probabilistic. A randomized sample is not useful in qualitative research, since generalizability to the general population is not the aim. Moreover with a random sample the researcher would run the risk of selecting people who have no link with the research subject and thus nothing to tell about it (Mortelmans, 2009). In purposive sampling the point of departure are the sampling criteria as described above. There are different forms of purposive sampling:
Table 9 – Example of stratified purposive sample
|
Already had eye surgery or surgery planned |
Considered eye surgery but refrained from having it |
|||||||||||||||||
|
Age |
20-30 |
31-40 |
>40 |
20-30 |
31-40 |
>40 |
||||||||||||
|
Socio-economic status |
a |
b |
c |
a |
b |
c |
a |
b |
c |
a |
b |
c |
a |
b |
c |
a |
b |
c |
|
Number of respondents |
2 |
2 |
2 |
2 |
2 |
2 |
2 |
2 |
2 |
2 |
2 |
2 |
2 |
2 |
2 |
2 |
2 |
2 |
Recruitment strategies
In order to achieve the expected sample, several ways to find and recruit participants could be suggested:
“Determining adequate sample size in qualitative research is ultimately a matter of judgement and experience in evaluating the quality of the information collected against the uses to which it will be put, the particular research method and purposeful sampling strategy employed, and the research product intended” (Sandelowski, 1995, p. 199).
Typically, in qualitative research one should continue sampling until saturation is reached– this is the point at which no new information or themes are emerging from the data35. Therefore sampling goes hand in hand with data analysis and cannot be planned totally in advance. In reality in every research institution, the sample size is also determined in function of the budget, the time and human resources available. This means often practical aspects of the research project may constrain the size of the sample before theoretical saturation is reached. This is also true for KCE working practice, since budgets and time schedules are limited and fixed.
Beware that saturation can be reached prematurely if one's sampling frame is too narrow, if one's analytical perspective is biased or limited; if the data collection method is not resulting in rich, in-depth information or when the researcher is unable to get beyond the surface.
First contact with a respondent
Box 1: Information to be given during first contact
Background information
Person responsible for the research
Arguments pro praticipation
Costs of the participation
Source: Adapted from Emans, 1986 cited by: Mortelmans, 2009
It is important that people understand that participation in interviews or focus groups is completely voluntary, and that they may choose to leave at any time during the discussion. In addition, it is imperative that participants are aware that they will receive no tangible benefit for participation. That is why the question on offering incentives is often rather contentious (Green et al., 2009). Nevertheless their traveling costs could be reimbursed or they can receive a slight compensation or a small gift.
Also it is recommended to leave the choice of place (where the interview will take place) up to the respondent, in order to facilitate his participation. The context in which the interview takes place determines partly the interactions during the interview. For example a patient at home or in the waiting room of a hospital will disclose other kinds of information, not only because he/she feels more or less comfortable, but also because the setting triggers other associations and thoughts. The interviewer/researcher should be well aware of and anticipate the impact the interview location is likely to have on the data generated.
The same accounts for the characteristics of the interviewer. In the qualitative interview the researcher empathizes with his or her respondents and views their situation from their own points of view53. In general this empathic stance as well as gaining trust from the respondent, is facilitated if the interviewer resembles the respondent in terms of race or other characteristics relevant to the research topic. Gender however is an exception to this rule. There is a debate in the literature about whether same sex or opposite sex is preferable in order to achieve rapport during interviews. Some argue that men are more comfortable in talking with women (especially about intimate topics) that they are with other men (Williams, 1993).
An interview guide should be adapted to the language and vocabulary of the participant(s) and is generally built out of three components:
A topic list covers all the topics the interviewer should ask during the interview. It enables the interviewer to guide the interview while allowing the discussion to flow naturally. The sequence of topics generally moves from the general to the specific. The sequencing of topics can be introduced in a flexible way, and within a general framework of topics, the focus of the discussion can be reset. A topic list is also used in preparation of the semi-structured questionnaire
In a questionnaire semi-structured questions are formulated in speaking language and are posed as such during the interview. The same questions with the same formulation, sometimes in the same sequence, are posed in each interview. The disadvantage however is that it can threaten the natural flow of the conversation.
Both for the topic list and the semi-structured questionnaire, questions/topics should evidently be selected in function of the research objectives. An open ended-formulation of the questions is important in order to enable the interviewee to talk freely without predispositions of the interviewer influencing the narrative. For example, rather than asking “Did you worry about the surgery?”, one could ask “How did you feel about the surgery?”.
A topic list or questionnaire may be adapted or improved in the course of the research, in line with the iterative nature of QRM. The more interviews you have done, the more you know and the more specific or detailed your questions can be (Mortelmans, 2009). However, continuity should be guarded. The topics of the first interview should also be represented in the following interviews, although the latter can also contain much more detailed questions.
For an example of a topic list and a semi-structured questionnaire, see Appendix 6 and Appendix 7 respectively.
The interview starts with an easy opening question which is mostly to set the interviewee at ease, break the ice and get to know each other. With this question the researcher does not expect to get a lot of useful information, the main function is to start up the conversation.
After that the conversation is started with a first general and easy to answer question addressing the content of the research. It can be an attitude question to enable the respondents to roll into the conversation. An example could be: “If you hear breast cancer screening, what are your first thoughts?”.
Next, transition questions involve the respondents in the research subject, for example through asking questions about personal experiences or specific behavior regarding the topic. Attitudinal questions are more difficult to answer and should therefore be addressed later in the interview. An example is “How did you experience your eye surgery?”.
Subsequently the key questions are addressed. These questions are the reason why the interview is done. The interviewer can make clear that the interviewee can take some time to answer these questions. An interview can count up to five key questions each taking up to fifteen minutes to answer them.
Finally, the interview is terminated by means of a concluding question and thanking the interviewee for his participation. Three types of concluding questions can be distinguished:
It is useful to conduct a pilot (focus group) interview in order to test, assess and validate the format and the appropriateness of the topic guide or questionnaire.
Preparations for the interview encompass the recruitment of participants and the making of appointments, becoming knowledgeable about the research topic, including learning the interview guide by heart, anticipating questions of participants regarding the research project, access to a physical space where the interviews can take place and preparation of the recording equipment (Mack,2005). Well functioning of the recorders is crucial, so batteries, tapes and microphones should be carefully checked. It could be practical to foresee a second recorder as back-up. Finally also a notebook, a pen, and of course the topic list or interview guide you prepared for the interview should not be forgotten.
Box 2: What to take to the interview?
Equipment
Interview packet
Source: Adapted from Mack, 2005
Informed consent should be obtained from each participant before starting the interview. Also permission should be asked to record the interview. Also it should be explained how the tapes will be used and stored.
The research aims should be briefly repeated. Probably the research aims were already explained during the first contact with the respondent in order to convince him of participating. Next, all the topics or questions on the checklist or questionnaire need to be addressed. Participants are probed for elaboration of their responses in order to learn everything they want to share about the research topic54. Mobile phones should be switched off during the interview so as not to imply that the participant’s testimony is of secondary importance.
During the interview back-up notes could be taken, the interviewee’s behaviors and contextual aspects of the interview should be observed and documented as part of the field notes. Field notes are expanded as soon as possible after each interview, preferably within 24 hours, while the memory is still fresh (Mack,2005).
To get deeper or redirect the discussion, probing techniques can be used:
The interview is closed by thanking the participant(s).
Transcribing is the procedure for producing a written version of the interview. Ideally, the information recorded during the interview will need to be transcribed in order to enable accurate data analysis. A transcript is a full written literal text of the interview. It often produces a lot of written text.
Good quality transcribing is not simply transferring words from the tape to the page. The wording communicates only a small proportion of the message. A lot of additional information is to be found in the way people speak. Tone and inflection, timing of reactions are important indicators too. With experienced observers and note-takers, a thematic analysis of the notes taken during the interviews could be used as a basis for analysis of the “non-verbal” aspects.
Transcribing is a time consuming and costly part of the study. The research team should consider in advance the question "who should do the transcribing”? Resources may be needed to pay an audio typist, a strategy usually more cost effective than a researcher. Be aware that “typists” are often unfamiliar with the terminology or language used in the interviews which can lead to mistakes and/or prolong the transcribing time.
It may not be essential to transcribe every interview. It is possible to use a technique known as tape and notebook analysis, which means taking notes from a playback of the tape recorded interview and triangulating them with the notes taken by the observers and note-takers. However, bias can occur if inexperienced qualitative researchers attempt tape and notebook analysis. It is certainly preferable to produce full transcripts of the first few interviews. Once the researcher becomes familiar with the key messages emerging from the data tape analysis may be possible. Transcripts are especially valuable when several researchers work with the same data.
In the following paragraph we mention a number of common pitfalls typical for interviews. They are based on the work of Mortelmans (Mortelmans, 2009) and the Qualitative Research Guidelines Project (Cohen, 2008).
Interviews are used in many contexts (journalism, human resource managers, etc.) and for many purposes (entertainment, recruitment of personnel, etc.), hence scientific data collection is only one very specific application, which should not be confused with other applications. The interview is easily trivialized as it is common practice in the media landscape which surrounds us. Fontana and Frey even speak about “the interview society” according to Atkinson and Silverman. Practicing health professionals routinely interview patients during their clinical work, and they may wonder whether simply talking to people constitutes a legitimate form of research (DiCicco-Bloom et al,2006). In qualitative research, however, interviewing is a well established research technique and two types can be distinguished: semi-structured and unstructured. Structured interviews are out of scope here, because they consist of administering structured questionnaires producing quantitative data.
Unstructured interviews are more or less equivalent to guided conversations(DiCicco-Bloom et al,2006). Originally they were part of ethnographers’ field work, consisting of participant observation and interviewing key informants on an ongoing basis to elicit information about the meaning of observed behaviors, interactions, or artifacts (DiCicco-Bloom et al,2006). There is no list of questions, nor an interview guide, the questions asked are based on the responses of the interviewee, as in the natural flow of a conversation (Britten, 1995).
Semi-structured interviews are often the sole data source in a qualitative research project. A set of predetermined open-ended questions is used to guide the interview, but other questions emerging from the dialogue can be added (Britten, 1995). Also the iterative nature of the research process in which preliminary data analysis coincides with data collection, results in altering questions as the research process proceeds. Even so, questions that are not effective in eliciting the necessary information can be dropped or replaced by new ones (Britten, 1995).
Essentially an interview consists of someone who asks questions (interviewer), someone who answers these questions (interviewee) and the registration of those answers in some way (Mortelmans, 2009).
The interview as qualitative research method differentiates from other forms of interviewing used in varied domains. Mortelmans pays attention to four characteristics:
Individual semi-structured interviews are useful to:
Strengths:
Weaknesses:
See “How to plan the research design?”
Individual semi-structured interviews are usually conducted face-to-face and involve one interviewer and one participant. Phone conversations and interviews with more than one participant also qualify as semi-structured interviews, but, in this chapter, we focus on individual, face-to-face interviews (Mack, 2005).
The data collection tools to carry out interviews are topic lists, questionnaires and field notes. Topic lists and questionnaires are described here.
Researchers use field notes to record observations and fragments of speech. Field notes should be written up as soon as possible after the events to which they refer. If possible, short “aide-mémoire” or pocket dictaphones may be used in fieldwork settings, to facilitate later expansion of the notes into proper fieldnotes (Bloor et al, 2006). In the chapter on observational techniques field notes are addressed in more detail (here).
For general issues on sampling, see “Sampling issues in qualitative research: who and how many?”.
In the ideal scenario researchers plan, organize, carry out and transcribe the interviews themselves, to be completely immersed in the data, but in practice the interviews are often carried out by subcontractors and the transcriptions are often done by professional typists.
Preparations for the interview see “How to run the data collection” .
Physical organisation of an interview. Take the following rules into account:
See "How to prepare data for analysis", “How to analyse?” and “How to report qualitative research findings?” .
[1] We propose a example of a ‘standard introductive text’ in appendix.
A focus group is a particular technique in qualitative research. In order to do a focus group interview a group of individuals is gathered in function of their specific profile or characteristics to explore a limited number of “focused questions” (Sofaer,1999). Groups are generally homogenous on a or several criteria relevant to the focus of the discussion.
“In essence, a focus group is a small (usually 6-12 people) group brought together to discuss a particular issue (..) under the direction of a facilitator who has a list of topics to discuss” (Green and Thorogood, 2009, p. 111).
Focus groups are group semi-structured interviews used for the purpose of collecting information focused on a specific subject or area of concern, for exploration and discovery, in-depth understanding of a problem as it is experienced in context, to assess needs, preferences, attitudes and interests related (in the context of KCE research) to health and health care issues.
It differs from individual semi-structured interviews, as the interaction component is used to bring out insights and understandings in ways which questionnaire items or individual questions may not be able to do. The interaction between the moderator and the group, as well as the interaction between group members, may result in more in-depth information, and to elicit differing perspectives related to carefully designed questions. Focus groups are thus not to be considered as a pragmatic time saving substitute for individual semi-structured interviews (e.g. if for any reason the planning does not allow for individual interviews), as the methodological groundings of both techniques differ.
A focus group is not synonymous to ‘group interview’: For a focus group, people are recruited specifically to participate in a research protocol, using a certain method. It is a group interview in the sense that it gathers data simultaneously from different participants (Green and Thorogood, 2009) However it differs from a group interview in the importance that is attached to the interaction among participants. Participants might change their perspective during the focus group interview because of this interaction. In a group interview the interaction between participants is limited, and occurs mainly between interviewer and interviewees.
Figure 4 – Interaction patterns in a group interview versus focus group interview
Depending on sampling strategy and aims, group interviews can take several forms, e.g. consensus panel, focus group, natural group or community interview (Coreil 2005 cited by Green and Thorogood, 2009).
Focus groups can be used as a single research strategy, as well as in combination with other methods in a multi-method research strategy.
The principal feature of focus group interviews is interaction between participants. Kitzinger (2006, p. 22) highlights that this particularity could be used to:
The benefits from focus groups highlighted are:
The limitations of focus groups are related to the limitations of group interviews:
Since focus group interviews are a collective data collection technique requiring direct person-to-person contact (several people have to come together at the same moment and in the same place) a careful planning of all activities and related tasks is necessary.
The data collection by focus group could vary according to (Cohen et al, 2008):
During the preparation of the focus group interviews a set of topics or questions is developed and takes the form of a topic list or questionnaire. For the general principles, see here
A focus group interview is in most cases a structured group process structured by means of an agenda to keep the group focused and on track. A focus-group should be experienced as free-flowing and relatively unstructured, but in reality, the moderator must follow a pre-planned script of specific issues and set goals for the type of information to be gathered. An introduction of up to 15 minutes should be carefully planned, as well as a good opening question. In order to keep the time schedule, as several people are going to participate and answer to the questions, it is important to foresee a maximum duration for each question.
The use of a well designed guide is helpful to compare information from one group to another as it is expected to have more than one focus group for a given topic.
For general issues on sampling, see “Sampling issues in qualitative research: who and how many?”
The starting point for selecting participants for focus groups is to identify the unit of analysis. Is the unit of analysis “individuals for their personal opinions/experience/expertise”, or is it “individuals because they represent organizational perspectives”? It has a major impact on the people invited to the focus group interview and therefore it should be clearly described.
The sample of focus groups will consist of groups of people, instead of individuals. People who are invited to take part need to have an interest in the subject.
Ideally groups have to be internally homogenous on criteria relevant to the topic but externally heterogeneous between groups. Homogeneity in the group capitalizes on people’s shared experiences (Kitzinger, 2006).
It is best to select people who do not know one another, but have similar relationships with the topic being investigated (although it could in practice be difficult for particular topics). Selecting participants who are similar may help them to share ideas more freely and develop an in-depth analysis of a topic (homogeneous groups).
Sometimes, heterogeneous groups can be used after the primary analysis of homogeneous focus groups has started. Heterogeneous groups are used to “confront” diverging opinions. In general terms, heterogeneous groups are composed of representatives of all relevant stakeholders.
In this case, the researcher has to pay attention to potential power differences or inequalities between participants. This may prevent some people from talking freely during the discussion and by consequence prevent the collection of rich data (Kitzinger, 2006).
In the Belgian context, focus group interviews can be carried out with French-speaking or Dutch-speaking and even German-speaking, participants. It is advisable to conduct unilingual groups: it is easier and richer for facilitators and participants. For heterogeneous groups, like stakeholders samples, it could be difficult to separate people in groups according to their mother tongue. In this particular case, it is important that participants express themselves in their mother tongue and to be sure that every participant understands the other language. The moderator has to be thus perfectly bilingual.
A group of six to twelve people is sufficient for a focus group. The ideal size for a focus group is eight to ten respondents. In general, the smaller the group, the more manageable it is. From experience, a group of 6‑8 participants allows enough time for discussion and is easier to manage. Where the purpose is to generate in-depth expression from participants, a smaller group size may be preferable in combination with carrying out more focus groups to attain saturation.
In order to make sure that a group counts enough participants, it is advisable to recruit 25% more people than required (Green and Thorogood, 2009). If too few participants turn up, one should foresee an additional focus group to substitute for the low attendance.
The number of focus group interviews needed depends on the aims and available resources . It is almost impossible to give clear standardized guidelines on the number of focus groups needed.
It is methodologically important for both approaches to conduct at least two focus groups by ‘type of people’. Using only one focus group to arrive at conclusions is risky since the opinions expressed may have had more to do with the group dynamics (i.e. persuasive skills of one or two members) than a true sampling of the opinions of the population that the group represents. Even the preset number of two focus groups is generally too limited to make in-depth analyses, especially if the topics discussed are rather “broad” or general (see also paragraph analysis on continuous comparative method). Having two homogeneous groups that provide different results suggests that more information is necessary (data saturation is not reached). One rule of thumb is to conduct focus groups until they no longer provide any new information on the topic discussed.
3.1.3.8 Human resources necessary
Three people (from the research team) could chair the focus group interview:
As focus group have to be transcribed afterwards. It is also useful to engage the services of an audio typist.
For general principles see “How to run the data collection?”.
In the case of focus groups, once the group of respondents is gathered for the discussion, the moderator should give a brief introduction to set everybody at ease[1]. More concretely, the moderator should:
The Moderator will then begin the focus group interview by asking an ‘icebreaker question’ to facilitate the discussion in the group. Afterwards, he/she will come to the focus of the discussion.
Immediately after the focus group a debriefing has to be foreseen with the moderators/facilitators. The debriefing part is an essential step for the analysis. The debriefing exercise is best supported by a template of dimensions, upon which the moderator/facilitator team needs to comment (example in Appendix).
The facilitators should review the notes taken during the focus group and have a first assessment of clarity and understanding.
They should discuss, compare and record observations or impressions about the group not readily apparent from the notes.
Discuss and record any insights or ideas emerging during the interviews while they are still fresh in the mind.
See also part “How to run the data collection? ”
The length of the focus group should be between 1 and 3 hours.
Allow sufficient time at the beginning to welcome participants, give them an introduction and let them introduce themselves. This part should not take excessive time (about 10 minutes).
Data are collected through different sources: audio or video-taping can be considered. When focus group interviews are recorded, the equipment should be of good quality and easy to use (check batteries and microphone). For larger groups, it may be necessary to use two tape recorders or multi-channel equipment, strategically placed to maximize the probability of recording contributions from all participants.
“Field notes” are an essential part during data collection. They capture all of the essential “non-verbal” information during the focus group interview.
Information has to be collected in an unbiased manner (avoid to filter out information as pre-interpreting it as unimportant, especially in the first focus groups).
The context of statements made during focus groups should be documented (important for giving meaning to the statements in the phase of analysis).
Try to capture nonverbal behavior of group participants (nonverbal reactions of other participants after a participant statement may indicate consensus or disagreement).
For issues on analysis, see “How to analyse the data?”.
In the particular case of focus groups, separate analyses have to be performed on data gathered “within-focus group” and continuously compared “between focus group”. This is also an iterative process.
It is important that statements be understood in the context which they were made. Nonverbal communication observed during the interview can also be very informative.
For reporting, see part “How to report qualitative research findings”
Note that findings are reported by focus group as unit of analysis and not by person.
See section part “How to evaluate qualitative research?”
Vermeire et al propose a checklist specific to critical appraise the quality of focus groups in health care research articles in primary healthcare (Vermeire et al, 2002).