Participants in this research were from a random sample of 2000 children drawn from a population study carried out by The Icelandic Centre for Social Research (ICSRA).
Þátttakendur í þessari rannsókn eru úr tilviljunarkenndu úrtaki 2000 barna tekin út úr þýðisrannsókn framkvæmd af Rannsóknum og greiningu.