Interview logistics and guide
Interviewing is an important, though sometimes difficult task. There are several things to be
covered in interviewer training:
- Interviewers should be provided with an
overview of the outbreak situation and review the purpose of the questionnaire.
- Interviewers should also be aware of the
respondent selection process.
- Respondents will often ask the interviewer
how they got their contact information.
- A majority of the training should focus on
the questionnaire - how to use it, the intent and meaning of each question, and how to record
or code responses.
- Discuss how the interviewer should respond
to questions from the respondents.
- Questions should always be asked in the
same way for each participant. The interviewer should not prompt or lead the respondent to
answers, which could introduce bias into the study.
The logistics of conducting the interviews should be agreed at the start of the outbreak
investigation. This includes the hours during which it is acceptable to call, how to track the
calls, how many times should the interviewers call a prospective respondent, whether they
should leave a message if they get an answering machine, and what to do with completed
questionnaires. Finally, and most importantly, discuss confidentiality of the interviews and
questionnaires. At the interviewer training, it is good practice to provide materials to the
interviewers in a manual (what exactly is included in a manual will depend on the outbreak
situation). You might include a calendar to help track dates, a map of a facility, or
guidelines related to but not directly associated with the outbreak that might be useful if
there are questions. Also, you might create a list of frequently asked questions and answers
that can be used by interviewers as a quick reference tool. Interviewers might also find it
useful to have some background information available on the outbreak - the organism, an
epidemic curve, etc. Depending on each outbreak scenario, decide which interview method would
be most appropriate (face-to-face, postal or telephone) and why. The relative strengths and
weaknesses of these approaches are summarised in the table below:
Face to face interview
• Highest response rate
• Allows collection of complex data
• Time consuming
• Resource intensive
• Least resource intensive
• Lowest response rate
• Slow process
• Relatively high response rate
• Relatively quick
• Respondent must have a phone
Online self administered
• Quickest method of data collection
• Respondents must have the technology
• Data security issues
If data are to be collected by a postal questionnaire, particular attention will need to be
given to the design of the questionnaire. Clear instructions and formatting are important to
aid the navigation and completion of postal questionnaires. The questionnaire will need to be
short and avoid open or complex questions. Unlike in research studies, there may not be time
for a thorough pretesting or piloting of the questionnaire before it is used to collect data.
However, where possible the questionnaire should be at least completed by a convenient sample
of colleagues or others before use to identify issues with presentation, wording, navigability
or content. Whichever method is chosen, data collection should be preceded by an interviewer
script (or cover letter for postal questionnaires) explaining who is conducting the
investigation and why the investigation is taking place, giving assurances on data
confidentiality and security, and thanking respondents for their participation. The
questionnaire should be checked after completion, as this is the best time to clarify anything
with the respondent. In phone interviews, a courteous and knowledgeable interviewer can be the
difference between a hang-up and a completed questionnaire. By maintaining a professional, but
friendly, approach throughout an interview, an interviewer can obtain important information
that will help investigators identify the cause of an outbreak.
At the draft analytical study protocol stage itself, it is useful to decide how to manage
non-responders. They can be either withdrawn from the study or treated as missing values.