GermanyIcelandItalyPolandNetherlandsScotland
SettingPublic schools, 4 school types: Gymnasium, Gemeinschaftsschule, Regionalschule, HauptschulePublic schoolsPublic schools, 2nd class of secondary school and first class of high schoolPublic schools, 1 school type (Gymnasium)Public schools, 4 different school typesMainstream (state-funded) schools
LocationsSchleswig-Holstein, Germany; District of Kiel, Flensburg, Schleswig-Flensburg, and Rendsburg-EckernfördeSchools from each region (north, south, east, west) of Iceland in addition to the capital area (Reykjavík and surrounding municipalities)Piedmont region, Italy; Schools with head office in Turin or Novara provincesWielkopolska regionGelderland, Limburg, BrabantCentral belt of Scotland
Time of data assessmentNov–Dec 2009Jan–Feb 2010March–June 2010April-June 2010Dec 2009–June 2010Jan–Mar 2010
Eligibility criteria for schoolsLocation; Number of classes > 8; No special pedagogic education center; No participation in other studies of IFT-NordNumber of participating students > 100Location in Turin or Novara provincesLocation in Wielkopolska region; No special pedagogic education centerNo special pedagogic education center; No current participation in other studies of the Behavioural Science Institute, Radboud UniversityLocation in either Midlothian or East Dumbartonshire; Not providing special education; Not providing private (non state-funded) education
No. of schools potentially eligibleN = 104Not knownN = 578N = 253Not knownN = 14
No. of schools invitedn = 60n = 23n = 31n = 253n = 43n = 7
Invitation criteria for schoolsRandomConvenience samplingConvenience samplingAll eligible schoolsRandomSelected on the basis of deprivation, based on the most recent (2007−2008) nationally available data relating to the proportion of free school meals
No. of schools that agreed to participaten = 21n = 20n = 26n = 35n = 5n = 7
Eligibility criteria for studentsActive (“opt-in”) parental consent; Presence on the day of assessment or, if absent, willing to complete a questionnaire and return by post; Willingness to participatePassive (“opt-out”) parental consent; Students presence on the day of assessment; Willingness to participateActive or passive parental consent; Willingness to participate or, if absent, willing to complete a questionnaire and return by postActive (“opt-in”) parental consent; Presence on the day of assessment; Willingness to participatePassive parental consent; Presence on the day of assessment; Willingness to participatePassive (“opt-out”) parental consent; Presence on the day of assessment or, if absent, willing to complete a questionnaire and return by post; Willingness to participate (written informed) consent from pupil
No. of students examined for eligibilityn = 3544n = 2798n = 2953n = 5078n = 1706n = 3189
No. confirmed eligibilityn = 2754n = 2664n = 2668n = 4105n = 1423n = 2937
Reasons for nonparticipationNo parental consent (n = 515); absence (n = 264); pupil refusal (n = 11)No parental consent (n = 19); absence (n = 102); pupil refusal (n = 13)No parental consent (n = 100); absence (n = 175); pupil refusal (n = 10)No parental consent (n = 396); absence (n = 527); pupil refusal (n = 50)No parental consent (n = 18); absence (n = 265); pupil refusal (n = 0)No parental consent (n = 11); absence (n = 226); pupil refusal (n = 15)
No. participated in the studyn = 2754n = 2664n = 2668n = 4105n = 1423n = 2937
No. analyzedn = 2754n = 2664n = 2668n = 4105n = 1423n = 2937
Response rate78%95%90%81%83%92%