en: The research consisted of a total of 1293 adolescents (49% boys) in the 9 th grade of Reykjavík city elementary schools in the year of 1994 and then were followed up.
is: Alls náði rannsóknin til 1293 ungmenna (49% drengir) í 9. bekk í grunnskólum Reykjavíkur árið 1994 sem var svo fylgt eftir.