 In the Gothenburg study, a questionnaire for preschool teachers was used from which children with some potential psychiatric problems were classified into either a high-index or a low-index group.In the final investigation, there were 22 children (14 boys and 8 girls) in the high-index group and 60 children (52 boys and 8 girls) in the low-index group.These were compared with a randomly selected control group.