This dissertation consists of three essays examining the determinants of child developmental outcomes using the Canadian National Longitudinal Survey of Children and Youth (NLSCY). The first essay estimates the relationship between birth weight and cognitive and behavioral outcomes for children aged 0 to 13. Using family fixed effects models to control for household heterogeneity, I find that every ounce counts; additional birth weight for infants born weighing less than 2,500 grams (low birth weight infants) is related to better outcomes for measures of math ability, pro-social behavior and property offense. Additional birth weight for those born weighing 2,500 grams or more is related to higher scores of motor and social development and verbal competence for young children. The second essay, using a sample of Canadian boys and girls aged 10 to 15 in dual-earner families, finds that parental work schedules play an important role in adolescents’ engagement in risky behaviour, especially for boys. Non-standard parental work schedules (i.e. work during evenings, nights, weekends and rotating shifts) are positively related to fighting, drinking and trying drugs among boys and fighting among girls. In the third essay, I investigate relationships between symptoms of hyperactivity-inattention and being read to for a sample of children aged 2 to 4. The main finding, based on family fixed effects estimates, is that children who have higher hyperactivity-inattention are read to less. However, results from interactions suggest that this relationship is only present when the person most knowledgeable of the child (usually the biological mother) has less than a post-secondary degree or diploma.

The aim of this theses is to establish, with reference to relevant literature, what is the impact of selective primary prevention programs in several chosen classes from the viewpoint of the lecturers of these programs. The author lays out and describes in detail the concepts of risky behaviours, primary prevention of risky behaviours, selective primary prevention, lecturer of primary prevention programs and other concepts relevant to the subject at hand. In the research part of this theses, the author deals with a research problem formulated as follows: What is the impact of selective primary prevention programs in chosen classes from the perspective of the lecturers? The selected method is qualitative research. The specific chosen research tool is a half-structured dialogue, conducted with lecturers of programs of selective primary prevention with at least two years of experience in the field. KEYWORDS Risky behaviours; primary prevention of risky behaviours; lecturer of primary prevention programs; selective primary prevention; selective primary prevention programs.

Les accidents routiers restent un problème important du secteur public de la santé au niveau international, national et régional. L’Organisation Mondiale de la Santé estime que plus d’un million de personnes meurent chaque année à cause d’un accident routier et entre 20 et 50 millions sont blessées ("Global status report on road safety: time for action," 2009). Parmi les conducteurs tués dans des accidents routiers, les jeunes conducteurs représentent au moins un quart (OECD, 2006). Les causes principales des accidents routiers, telles qu’elles sont mises en évidence dans le rapport de 2004 de l’Organisation Mondiale de la Santé (Peden et al., 2004), sont : la conduite sous l’influence de l’alcool, la vitesse, la conduite en état avancé de fatigue, l’utilisation du téléphone portable, la visibilité réduite et les facteurs appartenant à la qualité de la route. A ces causes, pour les jeunes, il faut rajouter la recherche des sensations, l’excitabilité et l’influence des pairs (A. F. Williams, 2006). L’influence des pairs représente un sujet controversé dans la littérature de spécialité à cause des résultats obtenus. Une partie des chercheurs considèrent que la présence des pairs a un effet plutôt négatif (Arnett et al., 1997; Doherty et al., 1998; Moller & Gregersen, 2008), pendant que l’autre envisage plutôt un effet positif (Delhomme, 1994; Engstrom, Gregersen, Granstrom, & Nyberg, 2008; Rueda-Domingo et al., 2004; Vollrath, Meilinger, & Krager, 2002). Cette recherche analyse l’effet des pairs sur les comportements à risque des jeunes conducteurs roumains et français en utilisant la théorie du comportement planifié, mais aussi l’effet de différents types de pressions de la part des pairs sur le comportement du jeune conducteur. Les résultats ont mis en évidence que les normes subjectives et surtout les normes subjectives de la part des amis, contribuent significativement à expliquer l’intention de réaliser des comportements à risque comme le dépassement de la vitesse et la conduite sous l’influence de l’alcool. Les analyses comparatives ont montré aussi des différences entre les deux populations. Par exemple, pour la population roumaine, les normes se retrouvent plus souvent dans les resultats des analyses que dans le cas de la population française. En plus, les jeunes conducteurs français ont un point de vue plutôt instrumental envers la voiture, en tant que pour les jeunes conducteurs roumains, la voiture représente plutôt un moyen d’impressionner les autres. Un autre résultat intéressant souligne le caractère souvent situationnel de la prise de risques chez les jeunes conducteurs accompagnés par des pairs, mais aussi les implications d’un groupe d’amis à prise de risques élevée. Pour conclure, les résultats obtenus à l’égard du rôle des normes et de l’effet de la pression des pairs sur les comportements à risque des jeunes conducteurs sont encourageants. / Road crashes remain a significant public health problem at international, national and regional level. World Health Organization estimates that more than a million persons die each year in road car crashes and that 20 to 50 million other persons are injured in those crashes ("Global status report on road safety: time for action," 2009). Among the drivers that die in car crashes almost a quarter are young drivers (OECD, 2006). The main causes of car crashes identified by WHO are driving while intoxicated, speeding, driving while tired, phone use, low visibility and poor road conditions (Peden et al., 2004). To these causes, in the case of young drivers we can add sensation seeking, excitability and peer influence (A. F. Williams, 2006). Peer influence on young drivers’ behaviour is a controversial topic in the literature due to the rather contradictory conclusions of the researches on this theme. Some researchers have found a negative effect of peer presence (Arnett et al., 1997; Doherty et al., 1998; Moller & Gregersen, 2008), while others have found a protective effect (Delhomme, 1994; Engstrom, Gregersen, Granstrom, & Nyberg, 2008; Rueda-Domingo et al., 2004; Vollrath, Meilinger, & Krager, 2002). This research analyses the effect that peers can have on young drivers’ risky behaviours by using the theory of planned behaviour approach and by looking into the effect that peer pressure type can have on the young driver. The results highlight that subjective norms and especially friend’s perceived norms contribute significantly to explaining young drivers’ intention to speed or to drive while intoxicated. The comparative analysis showed some interesting differences among the two populations. For example, for the Romanian drivers norms play a much more important role in explaining risky driving behaviours that for the French population. Also, young French drivers perceive the car as having rather an instrumental role while Romanian drivers see it more like a way to impress. Another interesting result emphasizes on the situational character of young drivers risk taking but also on the implications that risk taking peers might have. Finally, the results obtained regarding the role of norms and the effects of peer pressure on young drivers’ behaviour are rather encouraging.

The aim of this research was to investigate the HIV knowledge and risk behaviours of students as well as to deteremine whether the youth are aware of and utilising loveLife services. This was demonstrated with the HIV knowledge and risky behaviours of respondents using loveLife as their source of HIV information. Data was gathered by administering open-ended and close-ended questionnaires to 152 South African students aged 18—25 years old studying at Johannesburg, Braamfontein tertiary institutions. These questionnaires were structured to include the following information: the demography , condom attitude scale, the current and previous sexual behaviours, socio-sexual orientation index (SOI), self-efficacy for protective sexual behaviours scale, HIV and AIDS knowledge and understanding questionnaire,as well as the loveLife exposure, participation and response questionnaire. The data analysis techniques included statistical techniques of frequency counts, cross tabulations, Chi Square tests of associations, Point Biserial correlations, two independent t-test and Mann-Whitney U test, which were applied to all quantitative data; whereas thematic content analysis was applied to the open-ended questionnaire (qualitative data). Results revealed that young people are aware of loveLife services but are not utilising them. Respondents generally had good but biased HIV knowledge and increased HIV sexual risk behaviours. However, insignificant associations were found between awareness and utilisation of loveLife services and HIV knowledge and understanding, and sexual risk behaviours. The implications of the current study and recommendations for future studies are discussed.