Includes bibliographical references (p. 156-211). Number of sources in the bibliography: 466 Thesis (Ph. D.) -- University of Cyprus, Faculty of Social Sciences and Education, Department of Education, 2020. The University of Cyprus Library holds the printed form of the thesis. Η έρευνα αυτή πραγματεύεται ένα πολύ σημαντικό θέμα που αφορά στην επίδραση του περιβάλλοντος μάθησης και των χαρακτηριστικών της προσωπικότητας σε όλες τις μορφές εκφοβισμού (σωματικός, λεκτικός, κοινωνικός/έμμεσος, ψηφιακός), αλλά και στις αρνητικές επιπτώσεις που έχει το φαινόμενο στην ψυχική υγεία των εφήβων (συμπτώματα κατάθλιψης, ανησυχίας και άγχους), από τη σκοπιά της εκπαιδευτικής αποτελεσματικότητας. Συγκεκριμένα, αυτή είναι η πρώτη έρευνα διεθνώς που εξετάζει την επίδραση του σχολείου και της τάξης όχι μόνο στις διάφορες μορφές εκφοβισμού, αλλά και στις στρατηγικές άμυνας που χρησιμοποιούν οι έφηβοι στην προσπάθειά τους να χειριστούν περιστατικά ψηφιακού εκφοβισμού και στις επιπτώσεις που έχουν αυτά στην ψυχική τους υγεία. Η έρευνα αυτή επιτρέπει τον έλεγχο της εγκυρότητας του Δυναμικού Μοντέλου Εκπαιδευτικής Αποτελεσματικότητας και ειδικότερα των παραγόντων που βρίσκονται σε επίπεδο σχολείου. Διερευνά, επίσης, την επίδραση των χαρακτηριστικών της προσωπικότητας σε όλες τις μορφές εκφοβισμού, αλλά και το πώς σχετίζονται τόσο τα χαρακτηριστικά της προσωπικότητας, όσο και οι στρατηγικές άμυνας με την ψυχική υγεία των εφήβων. Η έρευνα αυτή είναι νατουραλιστική στο είδος της και περιλαμβάνει δύο μετρήσεις (αρχική και τελική). Σε αυτήν έλαβαν μέρος σχολεία Μέσης Εκπαίδευσης (Δημόσια Γυμνάσια). Στην πρώτη φάση της έρευνας, που αποσκοπούσε στην εγκυροποίηση ερευνητικών εργαλείων, συμμετείχαν στο σύνολό τους 920 μαθητές που φοιτούσαν στην Α’, Β’ και Γ’ τάξη. Στην κύρια φάση της έρευνας συμμετείχαν 950 μαθητές, οι οποίοι φοιτούσαν στη Β’ και Γ’ τάξη. Για τη μέτρηση των διαφορετικών πτυχών που αφορούν στην πολιτική του σχολείου, όπως περιγράφονται στο δυναμικό μοντέλο, χορηγήθηκε ένα ερωτηματολόγιο σε όλους τους εκπαιδευτικούς που εργάζονταν στα εν λόγω σχολεία. Στην έρευνα έγινε χρήση ποσοτικής μεθοδολογίας και αξιοποιήθηκαν σύγχρονες και εξειδικευμένες μέθοδοι ανάλυσης δεδομένων. Συγκεκριμένα, η εγκυροποίηση των εργαλείων που στηρίζονταν σε διατακτικές κλίμακες έγινε με τη χρήση του μοντέλου Rasch, ενώ η εγκυροποίηση των εργαλείων που χρησιμοποιούσαν κλίμακα Likert έγινε με Μοντέλα Δομικών Εξισώσεων (Structural Equation Modelling). Για την ανάλυση και διερεύνηση των στόχων της έρευνας έγινε χρήση πολυεπίπεδων αναλύσεων και Μοντέλων Δομικών Εξισώσεων. Τα αποτελέσματα αυτής της έρευνας έδειξαν ότι υπήρχαν σχολεία που ήταν πιο αποτελεσματικά σε σύγκριση με άλλα, στον χειρισμό περιστατικών εκφοβισμού σε σχέση με τις κλίμακες που εξετάστηκαν (π.χ. μαθητές που ήταν θύτες ή θύματα εκφοβιστικής συμπεριφοράς μέσω παραδοσιακών μορφών εκφοβισμού). Ακόμα, σχετικά με τους μαθητές που έπεσαν θύματα ψηφιακού εκφοβισμού, η επίδραση του σχολείου και της τάξης δεν βρέθηκε να είναι στατιστικά σημαντική. Επιπλέον, τα αποτελέσματα έδειξαν ότι υπήρχαν τάξεις που ήταν πιο αποτελεσματικές από άλλες στο να βοηθήσουν τους μαθητές τους να αναπτύξουν συγκεκριμένες στρατηγικές άμυνας (π.χ. “Distal Advice”, “Retaliation” και “Helplessness/Self-blame”). Αξίζει να αναφερθεί ότι το σχολείο και η τάξη δεν φάνηκαν να έχουν επίδραση στις υπόλοιπες στρατηγικές άμυνας που εξετάστηκαν σε αυτή την έρευνα (π.χ. Close Support, Assertiveness, Acting Ignoring και Technical Coping). Μια επιπλέον συνεισφορά αυτής της έρευνας είναι ότι εξετάζει την επίδραση του σχολείου και της τάξης στην ψυχική υγεία των εφήβων (π.χ. συμπτώματα κατάθλιψης, ανησυχίας και άγχους). Τα αποτελέσματα έδειξαν ότι ούτε το σχολείο, αλλά ούτε και η τάξη είχαν επίδραση στην ψυχική υγεία. Σχετικά με την επίδραση των χαρακτηριστικών της προσωπικότητας, τα αποτελέσματα αυτής της έρευνας έδειξαν ότι χαμηλά ποσοστά «Συγκαταβατικότητας» και υψηλά ποσοστά «Νευρωτισμού» μπορούν να προβλέψουν εάν κάποιος μαθητής μπορεί να είναι θύτης ή μπορεί να πέσει θύμα παραδοσιακών μορφών εκφοβισμού. Όσον αφορά στην επίδραση των χαρακτηριστικών της προσωπικότητας στα θύματα ψηφιακού εκφοβισμού, τα αποτελέσματα έδειξαν ότι η «Συγκαταβατικότητα» έχει αρνητική επίδραση, ενώ ο «Νευρωτισμός» θετική επίδραση. Επιπρόσθετα, τα αποτελέσματα των Μοντέλων Δομικών Εξισώσεων έδειξαν ότι η «Συγκαταβατικότητα» έχει έμμεση αρνητική επίδραση στην ψυχική υγεία μέσω της στρατηγικής άμυνας “Retaliation”. Ακόμη, η «Εξωστρέφεια» βρέθηκε να έχει έμμεση αρνητική επίδραση στην ψυχική υγεία μέσω της στρατηγικής άμυνας “Helplessness/Self-blame”. Επιπλέον, οι στρατηγικές άμυνας “Retaliation” και “Helplessness/Self-blame” φάνηκαν να σχετίζονται θετικά με την ψυχική υγεία. Τέλος, η «Συγκαταβατικότητα» και η «Εξωστρέφεια» φάνηκαν να σχετίζονται αρνητικά με τις στρατηγικές άμυνας “Retaliation” και “Helplessness/Self-blame”, αντίστοιχα. Κατά συνέπεια, λαμβάνοντας υπ’ όψιν τα αποτελέσματα αυτά, θα μπορούσε να δοθεί περισσότερη έμφαση τόσο από ερευνητές, όσο και από φορείς χάραξης πολιτικής, στις στρατηγικές άμυνας που χρησιμοποιούν οι έφηβοι στην προσπάθειά τους να χειριστούν περιστατικά ψηφιακού εκφοβισμού, μιας και αυτές σχετίζονται θετικά με την ψυχική τους υγεία. Bullying in schools is not considered a new phenomenon. Early research on bullying was mainly concerned with the following three traditional forms of bullying: a) physical, b) verbal, and c) indirect, relational and social aggression. Over the past two decades, emphasis has also been given on a new form of bullying (i.e., cyberbullying), which makes use of the diverse range of technology now available. In addition, research on coping strategies that adolescents use to deal with this new form of online aggression is as young as the research in the field of cyberbullying itself. Based on the unique characteristics of cyberbullying, it is considered crucial to examine how adolescents cope with the experiences of cyber-victimisation and identify those coping strategies or personality traits that are related to the negative undesirable outcomes that these experiences may have on their emotional well-being (i.e., symptoms of depression, anxiety, and stress). As bullying is a group process, a lot of research has been conducted to investigate the impact of improving the school learning environment in an attempt to reduce this aggressive phenomenon in schools. Longitudinal studies have shown that students who are victimised feel a sense of helplessness that increases over time. These students may need adults at school to help them respond to bullying incidents, support them, and provide a model of appropriate social behaviour. Furthermore, taking in mind the contribution of international longitudinal research in the field of educational effectiveness, some recent effectiveness studies made use of the Dynamic Model of Educational Effectiveness in order to support schools in facing and reducing bullying. These studies revealed that factors included in the model are associated with the effectiveness status of the schools in regard to reducing bullying. These studies, though, have focused only on the three traditional forms of bullying and were not concerned with the extent to which students have ever experienced cyberbullying. In addition, these studies did not focus on the coping strategies students use to deal with cyberbullying or the negative impact that these experiences may have on their emotional well-being (i.e., symptoms of depression, anxiety, and stress). In this context, this study was the first (as far as we are aware) that aimed to measure school effectiveness regarding bullying behaviour (including cyberbullying), which can be attributed to differences in the school learning environment factor, as it is described in the dynamic model. Besides, another aim of this study was to examine whether schools and/or classrooms have an effect on helping students develop specific coping strategies, which would help them deal with cyberbullying incidents. Also, this study aimed to examine whether schools and/or classrooms have an effect on the emotional well-being of students (i.e., symptoms of depression, anxiety, and stress). Another aim of this study was to examine whether specific personality traits can predict both bullying perpetration, as well as victimisation via all forms of bullying. Moreover, this study used a multilevel framework to examine the phenomenon of bullying by investigating the impact of personality characteristics of students in order to identify whether specific personality traits are related to coping strategies and to symptoms of depression, anxiety, and stress. Thus, based on the results of this study, more information regarding the validity of the dynamic model will be provided and suggestions for policy development will be made. In an attempt to measure the main variables of this study, as described above, The Revised Olweus Bully/Victim Questionnaire (OBVQ; was used to collect data on the three traditional forms of bullying. The OBVQ was previously tested in the context of Cyprus and found to have . In addition, The Depression Anxiety Stress Scale (DASS-21; Lovibond & Lovibond, 1995), an already validated instrument that measures symptoms of depression, anxiety, and stress, that has been previously tested in different contexts was also used. Regarding an instrument measuring the personality characteristics of students, an already validated instrument was selected that was previously used in the context of Cyprus, which provided good psychometric properties ). Moreover, in order to measure the variables that refer to the school-level factors of the dynamic model, an already validated instrument was selected (Creemers & Kyriakides, 2012), which was used in previous studies where the validity of the dynamic model was tested. Nevertheless, an instrument measuring cyberbullying was not available. Therefore, two instruments were selected that were used in previous studies in other countries in order to measure cyberbullying. Both instruments were tested in a pilot study prior to the first phase of the data collection. The first instrument measured the extent to which students are either bullies or victims of cyberbullying (i.e., ), while the second instrument measured how students would cope with hypothetical experiences of cyberbullying and if they have ever experienced it (i.e., . For the purpose of the pilot study, two secondary schools were selected, and students who participated were attending Grade 7, Grade 8 and Grade 9. One of the schools that participated in the pilot study was later excluded from the school sample of the main study. Based on the results of the pilot study the revised version of The Coping with Cyberbullying Questionnaire (CWCBQ; Sticca et al., 2015) was selected to be used. For the main study, secondary schools were selected to participate. Specifically, schools’ principals who expressed their willingness to participate were informed about the procedure of the data collection, while confidentiality issues were taken into consideration. The final version of all the instruments was administered to students attending Grade 8 and Grade 9 at the beginning of the school year in 2016 (n=936), and at the end of the school year 2017 (n=950). For the measurement of the different aspects of schools’ policy, as they are described in the dynamic model, a questionnaire was administered to all teachers in each participating school in May 2017 (n=107), in order to give time to new full-time teachers to become familiar with all the aspects of their schools’ policy. In order to analyse the data collected both for traditional forms of bullying and cyberbullying, the extended logistic model Rasch was used. Furthermore, the validity of students’ responses to the instruments that measured depression, anxiety, and stress, as well as the personality characteristics, were checked by using Structural Equation Modelling techniques. Moreover, separate multilevel regression techniques were used to identify the effects of the school and/or classroom, as well as the effects of the school-level factors of the dynamic model on students who were bullies or victims via traditional forms of bullying, on students who experienced cyberbullying, on the coping strategies they use to deal with cyberbullying, on their emotional well-being (i.e., symptoms of depression, anxiety, and stress), and on their personality traits. Structural Equation Modelling techniques were also used to identify whether specific personality traits are related to coping strategies and to symptoms of depression, anxiety, and stress. The main findings of this study indicated that there were schools which were found to be more effective than others concerning bullying behaviour in regard to the scales that were tested (i.e., students who were “Bullies” or “Victims” of bullying via traditional forms). Furthermore, regarding students who experienced cyberbullying, the effect of the school and classroom was not found to be statistically significant. Additionally, the results indicated that there were classrooms (i.e., teachers) which were more effective than others in helping students develop specific coping strategies (i.e., “Distal Advice”, “Retaliation”, and “Helplessness/ Self-blame”). It was also found that there was no school or classroom effect on the rest of the coping strategies that were examined in this study (i.e., Close Support, Assertiveness, Acting Ignoring, and Technical Coping). Another contribution of this study is that it investigates the effect of the school and/or classroom on symptoms of depression, anxiety, and stress. Results showed that there was no school or classroom effect on students’ emotional well-being. In addition, regarding the impact of personality traits on traditional forms of bullying, the results of this study indicated that low levels of “Agreeableness” and high levels of “Neuroticism” may predict both bullying perpetration as well as victimisation via traditional forms. Regarding the impact of personality traits on students who experienced cyberbullying, the results showed that “Agreeableness” has a negative effect on cyberbullying behaviour, whereas “Neuroticism” has a positive effect. Finally, the results of SEM analyses revealed that “Agreeableness” has an indirect effect on “General Distress” (i.e., symptoms of depression, anxiety, and stress) through the coping strategy “Retaliation”. In addition, “Extraversion” was found to have an indirect effect on “General Distress” through the coping strategy “Helplessness/Self-blame”. Also, “Retaliation” and “Helplessness/Self-blame” were found to have an effect on “General Distress”, while the personality traits of “Agreeableness” and “Extraversion” were negatively related to “General Distress”. Additionally, the personality trait of “Agreeableness” was found to be negatively associated with the coping strategy “Retaliation”. Similarly, “Extraversion” was found to be negatively associated with the coping strategy “Helplessness/Self-blame”. Thus, based on these results, more emphasis should be given by researchers and policymakers on the coping strategies students use to deal with cyberbullying, which have a more direct effect on their “General Distress”, rather than their personality characteristics. Implications of findings for theory and practice are finally drawn.