The research project "Processes of Excessive Internet Use in Families" (German: Verläufe exzessiver Internetnutzung in Familien: VEIF project) investigates how the use of the internet by adolescents is related to the situation in their family and the parental educational strategies with regard to digital media. Almost every young person in Germany uses the Internet, but the VEIF project focused specifically on excessive use of the Internet (hereafter referred to as "excessive use of the Internet") in the foreground. In addition, it was ascertained which strategies parents use to influence the internet use of their children and how well the exchange takes place in the family (so-called "family functionality"). In order to be able to examine the relationships over time, a total of three times the data has been collected annually. In each case, a young person (for the first interview between 12 and 14 years old) and a parent of this adolescent were questioned by trained interviewers directly in their home environment. The first data collection took place from January to March 2016 with a total of 1095 adolescents and 1095 parents. The second survey took place from January to March 2017 and 985 of the 1095 adolescents as well as 985 parents could be interviewed again (panel mortality after one year: 10.0%). The third survey was conducted between January and March 2018 and again 852 family dyads participated in the study (total panel mortality after two years: 22.2%). From the data of the available surveys, interesting results were obtained. Excessive use of the internet by young people in the third survey is compounded by familial aspects such as greater control, less communication within the family and stronger emotionality. In addition, as a parental media education strategy, greater technical mediation and in addition greater inattentiveness of adolescents are also relevant. The longitudinal findings from the three survey waves of the VEIF project expand the international state of research, which in the central topics (familial aspects and media education) apart from the studies from Asia by Chen et al. (2015) as well as from the working group of Shek and Yu (Yu / Shek 2013) so far consists exclusively of cross-sectional investigations. The importance of inferior family functionality for excessive Internet use has been demonstrated empirically both in cross-sectional (Ko et al., 2007) and longitudinally after two years (Yu/ Shek 2013), whereas after five years (Shek/ Yu 2016), none found statistically significant relationships more. The results from the VEIF project, which currently allow statements about the course of two years (time interval between first wave (W1) and third wave (W3)), point in a similar direction. Various aspects that affect the functionality of a family (e.g., greater control and emotionality) are also predictors of excessive Internet use in adolescence two years later. With regard to media education, the published (cross-sectional) studies mainly showed evidence of the protective effect of restrictive parental internet mediation (Chng et al., 2015) for excessive internet use, which could not be confirmed in the VEIF project over two years. However, according to the VEIF findings, the stronger technical mediation is also associated with excessive internet use two years later, and in addition, the construct of inconsistent media education, which was examined for the first time, seems to be relevant at least in cross-section. The findings of the VEIF project show the important role played by the mental health of adolescents, the family situation and parenting strategies for the development of excessive Internet use in adolescence.

Currently there are data available for three measurement times (W1 to W3). Accordingly, in the following, on the one hand, results in cross section (based on data from three survey waves) and, on the other hand, longitudinal data (based on the data of W1 to W3) or the development over the period of two years can be presented. The central questions of the VEIF project relate to the connection between excessive Internet use during adolescence and family functionality/ family climate and parental media education. The Young Diagnostic Questionnaire (YDQ, Young 1998) in W1 through W3 assessed excessive Internet use in the self-assessment of young people. In addition, the Compulsive Internet Use Scale by Meerkerk et al. (CIUS, 2009), since this questionnaire (in contrast to the YDQ), however, a uniform cut-off value still lacks internationally and thus many statistical evaluations (eg on the temporal stability of excessive internet use) can not be carried out with clear results Fi-nally, the YDQ was chosen as a more suitable survey tool. The familial aspects were raised during the last three waves with the family arches (FB-S, Cierpka/ Frevert 1994) for the adolescents, an additional parental assessment with the family questionnaires (FB-S) was only once supplemented to W1. Parental media education was measured using four scales of the EU Kids Online Project (Dürager/ Sonck 2014) and a newly developed scale that identified "Inconsistent Media Education Behavior". For this project, the data of the 852 of the 1095 family dyads were used, which could be interviewed at all measurement times. The central socio-demographic parameters of the sample remained largely unchanged for W1 and W3, with only the mean age of the sample increasing by about two years as expected. Excessive internet usage (sum value of the YDQ ≥ 5) reported a total of 15.3% of the interviewed adolescents in W1 and 10.2% two years later on W3. There was a low stability of excessive internet usage over two years (kappa coefficient of 0.27). A total of 41 adolescents (or 4.8% of the 852 respondents) are above the cut-off value of the YDQ for both W1 and W3. An additional 99 adolescents (11.6%) reported excessive internet use for W1 but not for W3 and 46 adolescents (5.4%) for W3 but not W1.

In the following, the main findings of the longitudinal analyzes, the correlations between W1 and W3 (two years later) are reported. If only the dimensions of the family functionality were taken into account at the first measurement point alone, only a few statistically significant correlations to excessive Internet use were found in the longitudinal analyzes two years later (W3). In addition to a more excessive use of the Internet, only a more pronounced parental emotionality (in each case raised to the W1) was a predictor of more excessive use of the internet by young people as part of the W3. At the first measurement point alone, if only the strategies of media education were taken into account (and the results for excessive Internet use were adjusted to W1), the longitudinal analyzes showed several statistically significant correlations to excessive Internet use two years later (W3). In addition to a more ex-cessive use of the Internet, there was a stronger technical mediation from the point of view of the adolescents and a stronger active mediation from the perspective of the parents. In addition, a comprehensive model was compiled which included not only aspects of family functionality and parental media education, but also socio-demographic characteristics, quality of life (Kidscreen-10 questionnaire of the Kid-screen Group Europe, 2006), and the mental health of the adolescents [Scales of Screening mental disorders in Youth-Alder-II by Hampel and Petermann (2012) and the scale "hyperactivity / inattention" from the Strengths and Difficulties Questionnaire of Goodman (1997)]. In the overall model, from the point of view of youth, excessive Internet use, greater control and technical mediation, and parental views showed better communication, greater emotionality, and more pronounced adolescent hyperactivity / inattention as statistically significant predictors (all raised to W1) for a more excessive Internet use to W3.

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