Reliability was established with twelve subjects interviewed by one interviewer with the second rater present but not participating in the interview process.
The interview takes approximately 40 min to complete, and is administered by a trained interviewer with experience in interviewing and qualitative analysis.
Patients were interviewed by a trained interviewer with a standardized questionnaire.
Qualitative data was obtained from in-person interviews by a single interviewer with 36 of 66 who had undertaken specialist training through FSMed (see Fig. 1).
During the first study visit, the mothers completed questionnaires and participated in a semi-structured interview with a trained interviewer with the child not present.
The interview takes approximately 40 min to complete and is administered by a trained interviewer with experience in qualitative analysis and interviewing.
The average interview duration was monitored for each interviewer with the intention of minimising respondent burden and keeping within the study budget.
Overall, 385 eligible cases and 424 controls agreed to further risk factor interviews administered by a trained nurse interviewer, with the final study consisting of 370 cases (96% of eligible) and 390 controls (92% of eligible).
The telephone interviews will be conducted by an experienced interviewer with a pre-determined set of questions.
Both the focus group and telephone interviews will be conducted by an experienced interviewer with a predetermined set of questions.
Children who participated in the cognitive interviews spent approximately 1 hour with each interviewer, with some children (for example, younger children who took breaks) requiring additional time.
