Resources required
1. Trained interviewers
Dietary recalls require a trained interviewer to undertake the dietary assessment in person or via telephone. An assessment that comprises several 24-hour recalls may use a combination of face-to-face and telephone interviews. The training of the interviewer is of utmost importance to ensure that the dietary data acquired is as reliable and valid as is possible.
There are some crucial points about the interviewers and the training itself:
- Interviewers should have knowledge of local foods (or be provided with relevant background documents); this is particularly important when working with ethnically diverse populations. It is also important at a regional level that colloquial names for food and eating occasions are readily understood.
- It is useful for the interviewer to be familiar with the food coding system to be used. Coding of previously collected 24-hour recalls should be included as part of the training as this helps the interviewer to understand the questions to ask about specific foods.
- The interviewer must have good inter-personnel skills and should remain non judgemental in both verbal and non-verbal cues throughout the interview.
- Questions must not lead or be directive.
- Judicial use of probing questions must be made.
- Regular reviews of the quality of the data collected (ideally by those responsible for coding the 24-hour recalls) allows feedback to be given to the interviewers and helps maintain the quality of data collected.
Intensive training of interviewers was undertaken in the Intermap study to ensure the precision of the dietary data collected (Robertson et al, 2005). A 12-point checklist (refer to Robertson et al, 2005 for more details) was used during training to assess interviewers’ competence. Interviewers were rated on a scale of 1 to 4 on the following:
· Privacy of interview
· General manner of interviewer
· Introduction by the interviewer
· Use of non-directed questions
· Pace
· Manner of questioning
· Objectivity
· Probing
· Use of estimation tools
· Documentation
· Use of memory aids
· Review of recall
Training scripts from the Intermap study are available on the Examples and Links of this section of the website.
2. Resources to code data and convert to nutrients
The process of coding and conversion of data to nutrients is time consuming and labour intensive and requires trained diet coders and a nutrient database and analysis program. (see data processing section).
3. Portion estimation aids
The estimation of portion size in the 24-hour recall usually requires the use of aids such as food photographs, household measures or food models.