The Scottish Health Survey 2024 - Volume 2: Technical Report

1.4   Fieldwork procedures

1.4.1     Advance letters

Each sampled address was sent an advance letter that introduced the survey and to let the resident know that an interviewer would be calling to seek permission to interview. A number of versions of the advance letter were used in 2024; one for the main version A addresses, one for main version B addresses (with the biological module), and one for child boost addresses. A copy of the survey leaflet was included with every advance letter. The survey leaflet introduced the survey, described its purpose in more detail and included some summary findings from previous surveys.

For copies of the advance letters and survey leaflet, see the documents listed in Appendix A.

1.4.2     Making contact

Initial contact for both samples was made via the advance letter. Interviewers then visited respondents’ homes to attempt to gain agreement to participate in the survey. At initial contact, the interviewer established the number of dwelling units (DUs) and/or households (HHs) at an address and made any necessary selections (see Section 1.2.7).

In the main sample, interviewers attempted to interview all adults (up to a maximum of ten) and up to two children aged 0-15 (see Section 1.2) from the household. At child boost sample households, interviewers first screened for children aged 0-15. In those households where children were present up to two children were randomly selected for interview. Interviewers obtained the verbal consent of both the parent/guardian and the child before commencing the interview.

1.4.3     Collecting data

Interviewers used computer assisted personal (CAPI) interviewing for interviews done in-home and computer assisted telephone interviewing (CATI) for the telephone interviews.

At each co-operating eligible household (across all sample types), the interviewer first completed a household questionnaire, with information collected from the household reference person[i] or their partner wherever possible. This questionnaire obtained basic information (including date of birth and relationship to other household members) about all members of the household, regardless of age and whether they were eligible to take part in the interview. The computer assisted personal/telephone interviewing (CAPI) program then created individual questionnaires for each eligible participant in the household.

Where possible an individual interview was then conducted with all eligible adults and up to two children in a household. In order to reduce the amount of time spent in the home, interviews could be carried out concurrently.

In addition to an advance letter and general survey leaflet, participants were also given a more detailed leaflet describing the contents and purpose of the interview, and what will happen to information they provide (including a link to the survey Privacy Notice).

A separate version of this leaflet was used for children in both main and child boost households. Parents at child boost addresses were also provided with a leaflet containing background information on the survey. Copies of all the participant leaflets used in the survey are included in Appendix A.

Intake24 dietary recalls were completed via a link sent directly to participants within minutes of giving consent. The first recall was scheduled for the same day as the interview. The second recall was completed within seven days of the initial recall. For participants who requested assistance to complete the recalls the interviewer collected a phone number and arranged an appointment date and time for the first recall. This information was saved on a secure server with restricted access for the NatCen Telephone Unit. After the first recall was completed, the date for the second recall was arranged between the respondent and NatCen Telephone Unit interviewer.

1.4.4     Interviewing and measuring children

Children aged 13-15 were interviewed directly by interviewers, after verbal consent had been obtained from both the child and their parent or guardian. Interviewers were instructed to ensure that the child’s parent or guardian was present throughout the interview. Information about younger children (aged 0-12) was collected directly from a parent or guardian. Whenever possible, younger children were present while their parent or guardian answered questions about their health. This was partly because the interviewer had to take the child’s height and weight measurements (where possible), but it also ensured that the child could contribute information where appropriate (for example, about physical activity done during school time).

1.4.5     Feedback to participants

If participants wished, interviewers recorded their height and weight measurements within their information leaflet. Participants kept the information leaflet and thus had a record of their height and weight, if they wished.

Participants eligible for the biological module were given an additional document, the biological measurement record card. If participants had their waist measurement and blood pressure taken, then interviewers recorded their results on this card (if the participant wished). As before, participants could keep this measurement record card and thus had a note of their measurements.

For the biological module, interviewers were issued with a set of guidelines to follow when commenting on participants’ blood pressure readings:

• If a participant’s blood pressure was low, they were informed of symptoms to look out for and advised to contact their GP if symptoms persisted.
• If the participant’s blood pressure was mildly raised, they were instructed to advise the participant to contact their GP within 3 months.
• If the participant’s blood pressure was raised, they were instructed to advise the participant to contact their GP within 2-3 weeks.
• Finally, if the participant’s blood pressure reading was considerably raised, interviewers advised the participant to visit their GP within 5 days and interviewers were instructed to contact the survey doctor at the earliest opportunity. The survey doctor would then phone the participant and advise them to contact their GP as soon as possible.

Participants who participated in Intake24 were offered generalised dietary feedback based on their recalls, either online (by email or as a PDF) or they could request a printed version to be sent to them.