The governmental statistics agency Statistics Norway provided demographic data on age, sex, education, income, and marital status. Education was grouped into five categories. The income of fathers and mothers was totalled to reflect family income. The age of parents and adolescents was used as continuous measures. Marital status was used together with the personal identification numbers of husbands and wives to determine whether the parents of a child were living together as a married or cohabiting couple. Dissolved relationships included divorcees, people who never lived together, unknown, and deceased parents.
