The data are the first part of the Jyväskylä Longitudinal Study of Personality and Social Development (JYLS), in which the same individuals have been followed over 30 years. The first round of data collection surveyed 8-year-old children through peer nominations, teacher ratings, and two personality tests. The peer nominations were made in classroom settings under the supervision of the researchers. The pupils answered various questions, such as "Which of your classmates are tranquil and patient?" and "Which of your classmates try to get other's attention by fooling around?". The pupils were asked to choose about 3-5 classmates fitting the description for each question. There were altogether 33 questions characterising the following traits: self control, aggressiveness, anxiety, passivity, compliance, constructiveness, and activity. The peer nominations were factor analysed, and on the basis of the results, the pupils were classified into 6 extreme groups: the aggressive, the anxious, the aggressive and anxious, the controller extroverts (the constructive), the stable, and the stable introverts (the compliant). This classification was used in designing the judgment sample for the 8-9 year old boys' aggressiveness tests, and later in the 14-year-olds' interviews. The data include the extreme group classifications for 8 and 14-year-olds. The teachers were also presented with the same set of questions. In addition, they were asked to assess the pupils' anti-social behaviour, excessive withdrawal, ability to concentrate, positive developmental predictions, and school success. The teachers evaluated each pupil according to how characteristic of him/her the aforementioned types of behaviour were. The girls' behaviour was compared with other girls of same age, and the boys' behaviour with other boys. The children completed two personality questionnaires translated into Finnish: the Junior Eysenck Personality Inventory (Eysenck, 1965), and Personality Inventory for the Lower Forms of Primary School (adapted from Cattell & Coan, 1959). The values for the individual sections of the tests are not available, only the sum variables from the sections measuring different characteristics. The sum variables of the first test comprise the sections measuring neuroticism (31 sections), and social (20) and impulsive (26) extrovertness. In addition, there is a lie scale (17 sections). The second test (Cattel & Coan) includes 12 scales; masculinity vs. femininity, anxiety, timidity, attitude towards school, dominance vs. submissiveness, self-confidence vs. feelings of inferiority, altruism, egoism, emotionality, restlessness, sensitivity, cooperativeness, and reliance. Each scale consists of nine sections. Background variables included the respondent's gender, class, and the location of the school (suburbs or city centre).

2007