Table 1 Description of outcome measure, determinants and covariates
Measure (time of assessment) | Response categories/codes | Range of continuous variables and categories of categorical variables included in analysis |
|---|---|---|
Outcome | ||
Student-reported total daily intake of FV (follow-up) | ||
24-h recall questionnaire based on detailed questions on yesterday’s intake of FV on three different times of the previous school day. The fruit measure included max 100 g juice. Potatoes were excluded. Exclusion of outliers >1200 g/d | Number of portions and pieces of different fruits and vegetables | 0–1200 g |
Determinants | ||
Teacher-reported dose delivered of Boost curriculum (follow-up) | ||
“Which of the Boost curricular activities from the teacher manual mentioned below did you teach during the Boost intervention period September 2010–May 2011?” A similar question was asked for activities from the script for a Boost project week. | List of all Boost curricular activities to tick off (listed by number and name consistent with teacher manuals) | School-level dose: average number of Boost curricular activities delivered by teachers at each school |
Low (0 – 3.8) (reference group) | ||
Medium (3.9 – 6.7) | ||
High (≥6.8) | ||
Student-reported dose received of Boost curriculum (follow-up) | ||
Students were asked to rate how much they liked each of the Boost curricular activities they had been exposed to during the intervention period. Each activity rated by the student counted as one activity received by the student. We added up the activities received by each student and calculated the class- and school-average. | Short description of each Boost curricular activity | School-level dose: average number of Boost curricular activities received by students at each school |
3.6–12.3 (school mean) | ||
Class-level dose: average number of Boost curricular activities received by students in each class | ||
0–13.5 (class mean) | ||
Covariates | ||
Student-reported total daily intake of FV (baseline) | ||
(see outcome measure) | Number of portions and pieces of different fruits and vegetables | 0–1200 g |
Prior “treatment” at schools | ||
Principal-reports of the school’s focus on FV prior to participation in the Boost intervention (baseline) | ||
“Did your school prior to the Boost project focus on FV for example as part of project weeks or school projects?” | Yes | Yes |
No | No (reference group) | |
Principal-reported FV availability at school apart from the FV delivered as part of the Boost intervention (baseline) | ||
“Is it possible for students at year seven to buy the following at the school?: 1) Fruit 2) Vegetables/salad” | Yes, every day | Everyday |
Yes, most days | Most days or less (reference group) | |
Some days | ||
Never | ||
Dose delivered of other intervention components | ||
Teacher-reported dose delivered of the pleasant eating environment component (follow-up) | ||
“How often do you cut up FV when students eat FV during your lessons?” | Every time | School-level dose: proportion of teachers at each school cutting up FV every time/most times students eat FV in class |
Most times | ||
Some times | ||
Seldom | ≤50 % (reference group) | |
Never | >50 % | |
Teacher-reported (only Boost coordinators) dose delivered of parental Boost newsletters (follow-up) | ||
“During the school year, Boost emailed six parental newsletters for the Boost coordinators to post on the schools’ website for parents. How many of these were posted?” | No newsletters | School-level dose: number of posted newsletters at each school |
One newsletter | ||
Two newsletters | 0–3 newsletters (reference group) | |
Three newsletters | 4–6 newsletters | |
Four newsletters | ||
Five newsletters | ||
Six newsletters | ||
Socio-demographic factors | ||
Student-reported gender (baseline) | ||
“Are you a boy or a girl?” | Boy | Boy |
Girl | Girl (reference group) | |
Student-reported family occupational social class (baseline) | ||
“Mother’s/father’s job title” (written answer) | I High | High: I and II |
“Mother’s/father’s workplace” (written answer) | II | Medium: III and IV (reference group) |
Based on job title and place of work of the mother and father, each parent was coded into one of five occupation social classes or some additional groups using standardized coding principles. Family occupational social class was based on the highest ranking parent. Students who did not provide sufficient information to code parents into occupational social classes or additional groups were excluded from the analyses. | III | Low: V and 7 |
IIII | Unclassifiable: 6 | |
V Low | ||
6 Has a job, but information unclassifiable | ||
7 Social Welfare benefits | ||
Parent-reported family educational level (baseline) | ||
“Which school education do you have?” | Enrolled in education | High education: f |
“Which vocational education do you have?” (If you have more than one, please tick off the highest level of education) | Primary school | Medium high education: e |
Manual education | Low education/none: a-d (reference group) | |
Low theoretical education | ||
Based on completed education, mothers and fathers were categorized into one of five educational categories using national coding principles. Family educational level was based on the highest ranking parent. Unclassifiable parents were excluded. | Medium high theoretical education | |
High theoretical education | ||