As many participants were located thousands of kilometres away from the interviewer, contact by phone was what enabled data collection.
Similar data were collected from the controls, via the obstetric care worker (40%) or from the pregnant woman in a personal interview by phone by two of the investigators, who were experienced interviewers (60%) (JK, TV).
To do that, we have experienced interviewers speak by phone with a firm's plant managers, asking everyone the same 18 open-ended questions and following up with more questions until they have a good sense of the firm's habits.
Whilst interviewers were encouraged to debrief following difficult interviews by phoning the research team, at times some found it difficult, or awkward, to do so.
The surveys were generally performed as interviews in person by trained interviewers, with a minority of the interviews performed by phone.
Next, the interviewer contacted them by phone and the purpose of the interview was briefly explained.
One week later, the interviewer contacted them by phone, answered any questions they might have, explained the study, and looked for their willingness to participate.
Make sure you actually speak to the interviewer when calling by phone; if you get their voicemail, leave a message only requesting they return your call at their earliest convenience.
According to the stratification characteristics the interviewers recruited physicians by phone during their consultation hours until 250 primary care physicians and 250 specialists had completed the interview.
The first author and interviewer (UOM) contacted them by phone, gave them information about the study and explained that they could withdraw at any time without giving any reason.
