Looij-Jansen, P.M.v.d.

health variation study youth difference questionnaire data collection netherland consumption –june behaviour disorder school effect health service september youth health surveys adolescent 0.03 period collection alcohol result ficant signi survey november activity *** rotterdam analysis fruit holiday –february vegetable consumption fi ve periods service youth health care health indicators dif ficulties questionnaire effect sizes health examinations –december march signi ficant differences month signi ficant psychiatry vegetable –april problem child season seasonality ficultie –october january pattern pupil alcohol consumption july –august kovalenko /week self-reported health symptom school holidays affective disorder school nurses climate comparison dutch score effect size alcohol use youth health rotterdam area looij-jansen self-reported depressive mood separation anxiety disorder strength