3.1.1.1 How to plan the research design?

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

3.1.1.2 Sampling issues in qualitative research: who and how many?

Selection of participants

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.

Sampling approaches

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:

1. To have experienced or to have considered a refractive surgery. We want to explore both the pro and cons.
2. To be older than 20 and younger than 70. Refractive eye surgery is not an option for those younger than 20 or older than 70.

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:

• Stratified purposive sampling (Patton, 2002):      
  Purposive samples can be stratified (or nested) by selecting particular persons that vary according to a key dimension/characteristic (e.g. a sample of people from large hospitals, and a different sample with people from small hospitals) and the selection ideally represents the different positions within the ‘system’ or phenomenon under investigation. The stratification criteria are the equivalent of independent variables in quantitative research. The researcher should think ahead about independent variables which could provide new information regarding the research topic. For example, in the research project on refractive eye surgery we expected that reasons to chose or refrain from chosing for refractive eye surgery vary with age, with financial resources and can be different in the Dutch- and French-speaking part of the country. Therefore we added age, socio-economic status and region as criteria introducing heterogeneity. This results in the following matrix:
• Homogeneous sampling:   
  In the case of homogeneous sampling variation between respondents is minimised. Participants are chosen because they are alike, in order to focus on one particular process or situation they have in common ⁽Mortelmans, 2009) . However the homogenous character does not exclude comparisons between types of participants, because for example unanticipated dimensions might emerge from the data. It is also useful to take into account hierarchy, hence not to put for example nurses and specialists working in the same hospital together in a focus group, as this might create bias in the responses.This sampling strategy is used when the goal of the research is to develop an in-depth understanding and description of a particular group with similar characteristics or people on equal foot. For example for the KCE research project on alternative medicines ^48-50 only regular users were sampled.

Table 9 – Example of stratified purposive sample

3.1.1.3 How to develop an interview guide?

An interview guide should be adapted to the language and vocabulary of the participant(s) and is generally built out of three components:

1. A reminder of the goal of the research.
2. The main topics or questions, the interviewer wants to address during the interview.
3. Relaunching questions. They are an essential part of the interview. It may happen that the interviewee does not give an answer to the question or gives an unexpected answer. In that case the interviewer can probe in order to delve deeper. In case a respondent does mention an aspect you thought of in advance or you are particularly interested in, you can repose the question focused on that specific issue. For example the initial question could be: “Which difficulties you experienced after your surgery?”. The respondent mentions all kinds of worries and inconveniences, but you are particularly interested in the organization of after care. Hence you could ask: “How did you experience the organization of after care?”.

3.1.1.4 How to run the data collection?

Preparations for the interview

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?

Source: Adapted from Mack, 2005

Running the interview

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:

• Repeat the question but in a different wording.
• Summarise the anwer the relevant aspects of the interviewee’s answer, in an interrogative way. For example: “In sum, you say that…?”
• Probe explicitly, for example: “What do you mean?” or “Could you give me a second example?”
• Purposive probing, for example: “Why was it that you?” or “What happened then?”
• Repeat the last couple of words in an interrogative way. For example: “R: (…) I think it is dangerous and I don’t trust doctors”. I: ”You don’t trust doctors?”
• Introduce a short silence.
• Verbalise emotions, for example: “I can see that thinking of that discussion makes you very angry.”

The interview is closed by thanking the participant(s).

3.1.1.5 How to prepare the data for analysis?

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.

3.1.1.6 What are the common pitfalls?

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)}.

• The methodology needs to be transparent. Each step of the sampling, data collection and analysis should be described in sufficient detail, this means that it must enable other researchers to replicate the same study.
• The sample should be well constructed and described.
• Avoid dichotomous questions which elicit a yes or a no. In an interview we are especially interested in rich descriptions and we want the interviewee to talk a lot and elaborate on the topic of the question.
• Avoid double questions, for example: “Once you decided to have a screening, what was the next step? How did you proceed? How did it change the way you thought about potential risks?” The interviewee can not respond to all the questions at once and thus picks out one. This means the other questions are lost.
• Avoid the expression of value judgements or your own opinion, for example: “What do you think about the endless waiting times?” The word “endless” suggests irritation.
• Avoid to be suggestive, for instance by giving examples: “Which kind of difficulties did you encounter, like long waiting times, full waiting rooms etc?” This kind of examples provide the interviewee with a frame, which he will possibly not transcend. This way you loose what he would have answered spontaneously.
• Avoid a reverse of roles. The interviewee should not be asking you questions. An example could be: I: “What does it mean to you to be a patient?”, R: “I don’t know. What does it mean to you?”. If this happens you can say that you are willing to answer that question after the interview, but that you can not answer it during the interview in order not to influence the answers of the interviewee. A reverse of roles can be avoided if the interviewer introduces himself in a neutral way, for example as a researcher, but not as, for example a physician or an expert in an issue related to the topic/goal of the interview, in order for the respondent not to ask you too many questions on a particular condition or issue.
• Avoid letting the interviewee deviate to far from the topic or elaborates on irrelevant matters by returning to the question posed.
• Avoid being too jargony, but use a familiar terminology which does not need explications or definitions.
• The analysis should not be superficial but really in-depth. However it may not transcend the data. The data must always support the results.