prev next front |1 |2 |3 |4 |5 |6 |7 |8 |9 |10 |11 |12 |13 |14 |15 |16 |17 |18 |19 |20 |21 |22 |23 |24 |25 |26 |27 |28 |29 |review

MATERIALS AND METHODS

Study Population

Data were collected between February 2 and 17, 1998, from subject in grades 1 through 6, including students from all 33 public elementary schools, and subjects in grades 1 through 3, including students at 15 junior high schools in Tokorozawa, Japan. In all, 25,767 subjects responded to the questionnaire among 28,848 students. The response rate was 89.3%. Active parental consent for participation was obtained in the form of written permission.