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14.4: The interviewers

  • Page ID
    13224
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    4.1 Selection

    Interviewers should be selected with careful attention to the tasks they will be expected to perform. They must be seen by the respondents as individuals who can be trusted to keep sensitive and confidential information to themselves. They must be of pleasant disposition, and be well-mannered, well-dressed, reliable, and punctual. They must not make promises to respondents that they do not honour (for example, if they say they will return on a given day they must do so or, at least, send a message in advance to explain and apologize if they cannot). The study investigator must attempt to assess whether potential interviewers have these characteristics during initial selection processes, which should include written tests and interviews.

    In general, contracts of employment for interviewers should include a probationary period, during which their suitability is further assessed and at the end of which a decision about longer-term employment is made. In some countries, it is possible to offer initial contracts solely for the training period. If so, the trial can select more interviewers that are needed and train them. This has two considerable advantages. It gives the trial team much more time for a detailed assessment of their character and performance than is possible through a short written test and interview, and also it is possible to select the best potential interviewers at the end of the training period, which should have included actual pilot testing of their tasks in the field. Other interviewers who have performed satisfactorily can be put on a waiting list, so that they could be offered the job at a later date, without the need for a full training course if one or more interviewers drops out or falls sick. Even after this, there must be provision for removing an interviewer from fieldwork if their performance is unsatisfactory.

    If possible, interviewers should speak the same language as the respondents; otherwise, interviews will have to be conducted through interpreters, which is usually unsatisfactory (for the reasons outlined in Section 2), although it is sometimes unavoidable.

    The sex, age, and normal place of residence of an interviewer may be important. For example, in some societies, male interviewers are less likely to get reliable information from women and may even not be allowed by local custom to interview them at all. If interviewers clearly belong to the health services, replies may be biased towards support for those services. Well-educated interviewers may not be best for interviews with less educated respondents; substantial differences in social status between interviewer and respondent should be avoided. Young interviewers may not be regarded as reliable or trustworthy recipients of sensitive information by adults but may be best able to elicit sensitive information from other young people. Also, sometimes sensitive information may be more readily given to a stranger than to a member of the same community, provided the respondents are assured of confidentiality.

    The most skilled and reliable interviewers are not always the most intelligent or highly educated. Indeed, highly educated interviewers may be more likely to become bored with repeated administration of the same interview schedule, especially if they do not see a clear and feasible career path by which they can progress, for example, to being a supervisor or to getting the opportunity for further training.

    4.2 Training

    The training of interviewers might initially be done as a group exercise, with classroom-type teaching. This must be supplemented with practical exercises. These might consist of one interviewer administering the survey questionnaire to the trainer (or another inter- viewer or someone else), while others look on, followed by a critical evaluation and discussion of the interview with the group. The person acting as the respondent should not be expected to answer any sensitive questions honestly but can make up plausible answers.

    The draft interviewers’ manual (see Section 4.4) should be used extensively in the training process, so that, by the end of training, the interviewer should be familiar with all aspects of the manual and know which parts to consult for advice on queries about particular questions or aspects of field procedures. Also, the training process usually reveals aspects of the manual that need revision or further clarification.

    Only after interviewers have been through a preliminary training course should they be allowed to try out interviews in the community. Initially, such interviews might be done by pairs of interviewers, in the presence of a trainer, with detailed ‘post- mortems’ being conducted after each interview or series of interviews. The training process will merge with the processes of standardization (see Section 4.3) and validation (see Section 2.4) and should be continually reinforced throughout the trial through supervision visits and meetings, and, when necessary, refresher training courses.

    4.3 Standardization

    As discussed in Section 2.4, an interview must be both repeatable and reproducible. Standardization of interview technique within and between interviewers is necessary for reproducibility. Interviewers must be trained to follow instructions on the questionnaire, as well as all other instructions, exactly. This extends to asking all questions exactly as written, if this is appropriate. As well as questions, the introduction to the interview, explanations and definitions made to the respondent, and transition statements that explain a change of subject of the questions should be said as written. The points in the interview to use probes and prompts to get the respondent to reply more fully should also be clearly specified.

    Standardization may also apply to the place and time of interviews. For example, interviews conducted in a home and health centre will, in many circumstances, produce different responses.

    It is not realistic, however, to insist on interviewers being merely reading and transcription ‘machines’. They must have some leeway to add extra explanations and guidance when it is clear that a respondent does not understand a question or a definition. Interviewer training should cover this and detail the extent to which this is permissible. However, stress should be placed on following the written wording, whenever possible.

    Standardization needs a certain degree of regimentation, and this can act against rapport and personal contact. Since the wording of questions is laid down in advance, it is important to ensure that it is friendly and does not alienate the respondent. If different interviewers are getting different responses to the same questions, it is important to investigate why. For example, one of the interviewers may be deviating from the interview schedule and giving undue emphasis to part of a question. Different interviewers attempting to collect the same information from one respondent at different times will normally be a part of the validation procedures (see Section 2.4).

    No matter how well interviewers are trained and standardized against each other, it is as well to assume in the design of a survey that some differences will exist in the responses obtained by different interviewers. This will influence the way different interviewers are deployed for fieldwork. Not only is it important to record on the interview schedule who conducts each interview, so that differences between interviewers can be analysed, but also interviewers should be deployed in a ‘balanced’ way, so that interviewer differences are not confounded with other differences of potential interest. For example, in an intervention trial, each interviewer should question similar numbers of subjects from the intervention and control groups. The worst situation would be for one interviewer to question those in the intervention group and another interviewer to question those in the control group.

    4.4 Interviewers’ manual

    An interviewers’ manual should be developed for use during the field survey. This should be reviewed during the training programme for interviewers and revised, as necessary. Careful version control will be needed to ensure that the current versions of the manual and questionnaire match each other. The manual should give detailed instructions regarding how individuals are to be selected and approached for inclusion in the study and for each specific interview, and it should detail any special instructions regarding each question in the questionnaire and how the responses should be entered. It should include guidance on how to deal with unusual situations and how to code unusual responses. It should also outline what checks are to be conducted on completed questionnaires and how and when completed questionnaires should be submitted for data processing and analysis.

    During the conduct of fieldwork, regular meetings should be held of interviewers to discuss the progress and queries. When new problems arise, the solutions should be incorporated into the field manual, so that there is consistency in dealing with the problem in the future and a permanent record is kept of the solution adopted. The manuals held by each interviewer should be updated regularly, and the text should be kept electronically to facilitate this. Again, careful version control is essential, and any changes to the manual (or questionnaire) should be documented in the trial diary (see Chapter 16).


    This page titled 14.4: The interviewers is shared under a CC BY-NC 4.0 license and was authored, remixed, and/or curated by Drue H. Barrett, Angus Dawson, Leonard W. Ortmann (Oxford University Press) via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.