Page 63 - ON THE WAY TO HEALTHIER SCHOOL CANTEENS - Irma Evenhuis

comprehensiveness and feasibility of each proposed measurement method to assess availability and the criteria for accessibility were assessed with structured questions [161- 163]. Examples of questions are: “Is it possible to classify the offered products in the right food group?”; “What is your opinion about and which barriers/facilitators do you expect regarding selling fruit at the check-out counter?” Furthermore, participants could add extra items they considered important. The feedback on each element of the Canteen Scan was sorted, reviewed and summarised by NW and checked by EV and CR.
During two expert meetings (with six and four school canteen advisors, respectively)
from the Netherlands Nutrition Centre, the proposed methods and items were rated on
feasibility (yes, maybe, no), barriers/facilitators were discussed and any suggestions for adaptions were addressed. The ratings on feasibility were counted and a summary of discussion points per Canteen Scan element was made. Afterwards, all attendees received
and approved the conclusions that emerged. The results of the interviews and expert
meeting were discussed in the project team and used to improve the tool. 4
Based on the three steps (1a, 1b, and 1c), a paper version of the Canteen scan was developed.
2. Assessing content validity of the paper draft of the Canteen Scan
It is important to assess content validity to be able to review whether users understand the questions as intended. To gain insight into the content validity, we assessed the concepts relevance, comprehensibility and comprehensiveness [161-163]. The paper draft of the Canteen Scan was assessed by four different end-users (canteen managers and representatives of caterers) in four schools with a medium size canteen. Schools differed in canteen operator (n=2 by the school itself, n=2 by a caterer) and expected healthfulness of the canteen (n=2 healthier canteen, n=2 not healthy). End-users were instructed to conduct the Canteen Scan in their canteen, which included two options to quantify the available products. First counting the numbers of products and second counting the rows per product (called “facings”). Subsequently, a structured interview was performed to review the content validity by the concepts relevance (does the instrument contain only relevant aspects?), comprehensibility (are all aspects understood as intended, and are the response options appropriate?), and comprehensiveness (are no important aspects missing?). In addition, feasibility and recommendations were assessed [161-163]. Each concept was questioned per construct of the Canteen Scan. E.g. “Which method, counting or facings, represents the offer on display the best?” and “Is it feasible to select products you see first while moving along the route through the canteen?”). At least, general open questions were stated, e.g. “What is your opinion about the amount of time needed to fill-out the Canteen Scan?” In addition to the structured questions, the trained interviewer (NW) was allowed to probe questions if answers needed more explanation. NW sorted, reviewed and extracted the results, and this was checked by EV and CR. The summarised findings were discussed in the project team and used to further refine the Canteen Scan.
3. Pilot testing the online version of the Canteen Scan
The refined paper version of the Canteen Scan was translated into an online tool which was pilot tested for its usability among four end-users from four different school canteens, which differed in canteen operator and expected healthfulness of the canteen. Pilot testing
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