Why Does a Universal Anti-Bullying Program Not Help All Children? Explaining Persistent Victimization During an Intervention

The data used in this study came from the Dutch implementation of the KiVa anti-bullying program. KiVa provides materials to teachers from grades 3–6. These include lesson plans, discussion ideas, and suggestions for group work and role-playing, in which children are encouraged to stand up against bullying and support victims (Salmivalli et al. 2011). Further, parents receive an information guide about bullying, a school-wide KiVa team is installed to resolve existing cases of bullying, and throughout the school symbols are used, such as posters and highly visible recess vests for teachers, to remind students and school personnel of KiVa. Although previous research has established the effectiveness of the intervention in Finland (Kärnä et al. 2011) and the Netherlands (Veenstra 2015), knowledge about victimization trajectories after implementation of the intervention is lacking. The longitudinal evaluation data of the Dutch KiVa were used: children were followed from before the start of the intervention for 2 years, resulting in five data waves (T1 = May 2012—the intervention started in August, T2 = October 2012, T3 = May 2013, T4 = October 2013, T5 = May 2014).

Information about the study and consent forms were sent to parents prior to intervention implementation and assessments. Parents who did not want their child to participate in the assessment were asked to return the form. Students were informed at school about the research and gave oral assent. Both parents and students could withdraw from participation at any time. Students did not participate when parents refused participation, when they did not want to participate themselves, or when they were unable to complete the questionnaire. Non-response rates were low (T1 = 0.6%; T2 = 0.2%; T3 = 0.5%; T4 = 1.3%; T5 = 2.7%), largely because the data were collected digitally and students who missed the scheduled day of data collection could participate on another day within a month. Individual internet-based questionnaires were completed during regular school hours with primary teachers present to answer questions and assist students when necessary. The order of questions and instruments used was randomized to avoid systematic effects of question order. Assessments were identical in intervention and control conditions.

The intervention sample used here consisted of 6142 students in 65 schools (49.6% boys), with students in grades 2–5 at T1 (M_age = 9.14, SD = 1.28). Students were 79.7% Dutch, 3.5% Moroccan, 2.2% Turkish, 2.5% Surinamese, and 1.1% Dutch Antillean. The remaining children reported another Western (6%) or non-Western (5.2%) ethnicity. The control sample consisted of 2980 students (49.4% boys) in 33 schools, with students in grades 2–5 (M_age = 9.22, SD = 1.28). Students were 80.3% Dutch, 2.8% Moroccan, 1.8% Turkish, 2.5% Surinamese, and 1% Dutch Antilleans; 11.1% of students reported another Western (5.6%) or non-Western (5.5%) ethnicity.

Victimization (T1–T5) was measured via self-reports using the Olweus’ (1996) Bully/Victim Questionnaire. Children watched a movie in which bullying was defined (repeatedly harassing another child, and the victim has problems defending him or herself); after this, they responded to one global item (“How often have you been bullied during the past couple of months?”) and seven specific items concerning physical, verbal (two items), relational (two items), material (i.e., taking or breaking others’ property), and cyber victimization (i.e., receiving nasty or insulting messages, calls, or pictures). Children answered on a five-point scale (0 = not at all, 1 = once or twice, 2 = two or three times a month, 3 = about once a week, 4 = several times per week). Scales were internally consistent at all time points (α’s > .87).

Social anxiety (T2) was measured using a seven-item scale, derived from the Social Phobia Screening Questionnaire (Furmark et al. 1999). We used items from the original questionnaire that were appropriate for this age group, such as “I am scared to talk to someone whom I don’t know” (1 = never, 5 = always). The items formed a reliable scale (α = .77).

Depressive symptoms (T2) were measured using nine age-appropriate items from the Major Depression Disorder Scale (Chorpita et al. 2000). Children responded on a four-point scale to items such as “I feel worthless” (1 = never to 4 = always), α = .81.

Externalizing behaviors (T2) were measured using 13 items from the Youth Self Report Conduct Problem Scale (Achenbach 1991). Several items were slightly modified to improve applicability to this age group. Students responded on a three-point scale to items such as “I break rules at school or elsewhere” (1 = never to 3 = often), α = .81.

Self-control (T2) was measured using eight items from the Temperament in Middle Childhood Questionnaire (Simonds and Rothbart 2004) (e.g., “When someone tells me ‘Stop’, I can stop”). Students responded on a five-point scale (1 = never to 5 = always), α = .69.

Self-esteem (T1) was measured using five items based on the Rosenberg Self Esteem Scale (Rosenberg 1965) (e.g., “On the whole, I am satisfied with myself”). Only positively formulated items were used. Students responded on a five-point scale (1 = never to 5 = always), α = .82.

Popularity (T2) was measured by asking students to nominate the classmates they perceived as most popular (“Who are the most popular students in your class?”). Rejection (T2) was measured by asking students to name the classmates they disliked (“Which classmates do you not like at all?”). For each student, received nominations were summed and divided by the number of participating classmates, resulting in proportion scores for popularity (0–1) and peer rejection (0–1).

Parental warmth and rejection (T2) were assessed using the EMBU Warmth and Rejection Scale (Arrindell et al. 1983). We used four items from the original subscales (i.e., warmth and rejection) referring to both father and mother. Students responded on a four-point scale (1 = no to 4 = almost always) to questions such as “If things are not going right for you, does your father/mother try to comfort or help you?” (warmth) and “Is your mother/father sometimes harsh and unkind to you?” (rejection). The items formed reliable scales: maternal warmth (α = .85) and rejection (α = .73) and paternal warmth (α = .86) and rejection (α = .85). Answers for both parents were highly correlated, for warmth (r = 0.57, p < .001) and for rejection (r = 0.53, p < .001); thus, we used a composite.

The initial sample consisted of 10,838 students: 7302 students in intervention schools and 3536 students in control schools. We excluded students with fewer than three data points on the victimization variable to obtain valid trajectories. Among the 1650 students who were excluded for this reason (intervention 1116, control 534), 1609 (intervention 1093, control 516) were excluded because they were not pupils at the school at the time of at least two assessments, because they were in the last grade of primary school (grade 8) at T1 and did not take part in later assessments, or because they entered grade 5 in T4 and thus did not participate in earlier assessments. We also excluded participants with missing data on all predictors, as was the case for a small number of children who entered the school at a later date. No evidence for differences between excluded and included children on predictor scores were found.

Semi-parametric group-based models were used to identify the number and shape of distinct victimization trajectories using data from T1 to T5. The analyses proceeded in three steps. In the first step, we estimated the developmental models for victimization separately for control and intervention samples using latent class growth models in Mplus 7.1.4 (Muthén and Muthén 2015). We fitted a series of models beginning with a one-group model and moving to a four-group solution (cf. Barker et al., 2008a). All models were estimated with random starts, and variances within trajectories were constrained to zero. We estimated both linear and quadratic trajectories for each group. Bayesian Information Criterion (BIC), entropy, and Lo-Mendell-Rubin adjusted likelihood ratio test (LMR-LRT; Lo et al. 2001) were used to establish the best solution, and the theoretical meaningfulness of the best-fitting model was evaluated. Entropy was assessed to establish whether the most likely class membership could be used as grouping variable in subsequent analyses (> .91; Heron et al. 2015).

Next, we performed multinomial logistic regressions (using group membership as a dependent variable) to examine whether social standing, child characteristics, and relationships with parents influenced membership in trajectory groups. In all models, we controlled for children’s sex and, wherever we detected significant associations with the outcome, investigated whether associations varied by sex. Missing data remaining after the case selection procedure outlined above were handled using full information maximum likelihood estimation. We computed intra-class correlations (ICC) of the manifest variables of victimization at the classroom level. About 6% of the differences in victimization were between classrooms (ICC_class = .064 at T2 and .057 at T5). Therefore, we used a multilevel structure in which we used the cluster command in Mplus to take into account the dependent structure of the data. We estimated univariate as well as multivariate prediction of trajectory groups to identify which characteristics predicted group membership, above and beyond the variance attributable to other predictors.

The fit indices for the trajectory models in the intervention sample showed that the entropy of the two-group model (.945) was higher than that of the three-group model (.924), but BIC and LMR-LRT value indicated a better fit for the three-group model (two-group model BIC = 43,339.8, LMR-LRT < .001; three-group-model BIC = 40,988.1, LMR-LRT = .002). Although adding a fourth trajectory would have further improved the model according to the higher entropy value (.927), it would not according to the higher BIC value (51,807.2) and LMR-LRT (p = .727), and it would also have led to groups being too small to make meaningful group comparisons (< 3% of the sample; Haltigan and Vaillancourt 2014). Thus, we moved forward with the three-group model because this model was more parsimonious and allowed for a more meaningful interpretation.

The three trajectory groups (Fig. 1) describe persistent victimization (3.6%), decreasing victimization (15.3%), and no (or very low levels of) victimization (81.1%). The persistent (M_intercept = 1.70) and decreasing (M_intercept = 1.64) trajectories did not differ in initial levels of victimization. The non-involved trajectory (M_intercept = 0.42) started with lower levels of victimization than both other trajectories (p < .001). After the start of the intervention (T1), the development of victimization differed. In the persistent trajectory, victimization linearly increased (M_lslope = 0.35, p = .010) and leveled off over time (M_qslope = − 0.09, p = .013). In the decreasing trajectory, victimization linearly decreased (M_lslope = − 0.40, p < .001) and leveled off over time (M_qslope = 0.03, p = .030). The non-involved trajectory had the same shape as the decreasing trajectory, but the decrease in victimization was less steep in the non-involved trajectory (M_lslope = − 0.17, p < .001; M_qslope = 0.02, p < .001). Sex was not a significant predictor of trajectory membership, χ² = 1.96 (2), p = .375.

With respect to the control sample, a two-group model showed the best fit. This model described one low (86.8%) and one high (13.2%) trajectory. In the low trajectory (M_intercept = 0.46), victimization linearly decreased (M_lslope = − 0.15, p < .001) and leveled off over time (M_qslope = 0.02, p < .001). The high trajectory started with significantly elevated (p < .001) levels of victimization (M_intercept = 1.80) and decreased with a non-significant trend (M_lslope = − 0.09, p = .174; M_qslope = − 0.03, p = .087). Despite the fit indices suggesting a two-trajectory solution, we also estimated a three-trajectory model, describing one stable-low (79.6%), one medium (16.2%), and one stable-high (4.3%) trajectory. The medium trajectory (M_intercept = 1.80) showed a decreasing trend which was not significant, as indicated by the non-significant slope and quadratic effects (M_lslope = − 0.13, p = .059; M_qslope = − 0.02, p = .220). This overall pattern supports our expectation that KiVa would contribute to a decline in victimization, and justifies comparing the persistent and decreasing groups in the intervention condition only.

Means and standard deviations for victimization and predictors across trajectories are presented in Table 1 and correlations are presented in the Appendix (available online). Table 2 provides univariate estimates for the trajectory predictions. Contrasting victim trajectories (persistent and decreasing) with the non-involved trajectory shows that social standing, child characteristics, and problematic parent-child relationships predicted victimization (both persistent and decreasing) in both the intervention and the control sample.

Most relevant to our research question were predictions of membership in the persistent trajectory compared with the decreasing trajectory; for this we focused on the intervention sample (see first columns of Table 2). Membership in the persistent trajectory was more likely for children with high scores on peer rejection (OR = 1.15), social anxiety (OR = 1.35), depressive symptoms (OR = 1.36), and parental rejection (OR = 1.29), and a low score on parental warmth (OR = 0.74).

Table 3 provides predictions for contrasts between the persistent and the decreasing victimization trajectories when adjusted for all other predictors. Higher peer rejection (OR = 1.16) and social anxiety (OR = 1.29), and lower parental warmth (OR = 0.74) continued to predict persistent victimization when all other risk factors were taken into account.

Trajectory analyses revealed persistent, decreasing, and non-involved victimization pathways in the intervention sample, mirroring previous research on victimization development in which the three-group model represented the best-fitting solution, with a small group of persistent victims, a larger group of individuals who were less victimized over time, and a large group of non-involved children (Barker et al., 2008b; Biggs et al. 2010; Boivin et al. 2010). In our sample, the group of children on a decreasing victimization pathway (15.3%) seemed large compared with previous studies. Examples of the sizes of the decreasing victimization group in previous studies are 4.5% (Boivin et al. 2010), 6.6% (Sheppard et al. 2018), and 10% (Barker et al., 2008a); in our own control sample, we only found a stable high group with a (non-significant) decreasing trend. The obvious explanation for the relatively large group of decreasers in the intervention sample is that our sample was drawn from an intervention study. The larger proportion of children who decreased in victimization reflects the overall effectiveness of the intervention. Nonetheless, we also detected the hypothesized persistent victimization group. The size of the persistent group in the current study was somewhat smaller than in other studies (Barker et al., 2008a; Sheppard et al. 2018).

In line with previous findings, victimization was predicted by higher levels of social anxiety and depressive symptoms (Reijntjes et al. 2010), peer rejection (Salmivalli and Isaacs 2005), externalizing behaviors (Reijntjes et al. 2011), and parental rejection (e.g., Barker et al., 2008b; Kokkinos 2013), and by lower levels of popularity (Cook et al. 2010), self-esteem (Graham and Juvonen 1998; Guerra et al. 2011; Salmivalli and Isaacs 2005), self-control (Giesbrecht et al. 2011), and parental warmth (e.g., Barker et al., 2008b; Kokkinos 2013). Thus, regardless of their role in an intervention, these characteristics can be regarded as risks for victimization. Most notably, several characteristics not only differentiated victims from non-victims but also contributed to greater vulnerability to continuing victimization despite participation in a group-based intervention. Lower levels of risk factors for persistent victimization also predicted decreasing victimization. Thus, children who experienced slightly elevated levels of individual risk factors may still be able to benefit from a group-based intervention. Children with highly elevated levels of these internalizing and parent-child relationship problems, however, have difficulties taking advantage of such an intervention. Future studies could further examine what factors can decrease the levels of risk factors within the intervention, for example targeting internalizing problems or problems in the family context, so all children can benefit from a universal intervention.

Peer rejection predicted persistent victimization, perhaps because rejected children can recruit support from fewer classmates, and peers gain little from supporting a rejected child in terms of affection or status, rendering the KiVa strategy somewhat less effective. Further, rejected children tend to be more reactive and angry, and less able to self-regulate during distressing social situations, including victimization (Morrow et al. 2014). Bystanders may not recognize victimization situations where victims show such behaviors, and thus refrain from defending.

In line with theoretical assumptions, internalizing behaviors also predicted persistent relative to decreasing victimization over time. It is feasible that socially anxious or depressed children more often withdraw from social interactions or are considered less interesting or desirable for others to interact with. In turn, they miss out on the increased opportunities to create supportive bonds with peers established in group-based interventions (Hodges and Perry 1999). Alternatively, children with internalizing problems might have a tendency to interpret social situations in a negative or threatening manner; they might thus perceive peers’ behaviors as continued bullying (Miers et al. 2008) and be less likely to view their situation as improving.

Besides individual characteristics, children’s relationships with parents were also associated with persistency, suggesting that children who experienced negativity in parent-child relationships may have less adaptive social strategies and experience more difficulties in creating or sustaining the positive relationships that are emphasized by the intervention, because they feel less powerful and self-confident (Duncan 2004). They may also have problems with trusting others’ intentions; this mistrust may extend into peer situations that are central in anti-bullying interventions, such as establishing contact between bystanders and victims (Salmivalli et al. 2011). Less trusting victims may question their peers’ sincerity in creating positive social relationships with them when this contrasts with their behavior before the intervention (Ladd and Troop-Gordon 2003). Hence, these children might remain socially isolated from peers and have therefore more difficulty recruiting support. Alternatively, cold or hostile parents might be less likely to support their victimized children, or to notice or report their children’s victimization, and teachers would then be less likely to intervene.

In interpreting our results, some limitations need to be kept in mind. First, most measures were based on children’s self-reports, possibly resulting in inflated associations due to shared method variance. Further, self-reports of victimization might be influenced by different conceptions of what constitutes victimization and children’s abilities to remember instances of victimization. Therefore, it is important to note that in this study, we measured children’s perceptions of victimization. Future studies could incorporate multiple informants to elucidate whether similar trajectories arise when peers or teachers report on victimization.

Moreover, when examining potential risks for persistent victimization, we used assessments from the beginning of the intervention. However, these risks may change over time; for example, victims might become more self-confident during an intervention. Dynamic models could elucidate change over time in risk factors and associations with victimization trajectories, and would be a valuable application in future work.

The current study did not go beyond children and their individual relationships. Characteristics at other levels, such as the classroom, also predict victimization (e.g., Cook et al. 2010; Hong and Espelage 2012). Although tentative, such characteristics might contribute information as to why some children benefit more from an intervention. However, in every classroom where there was a persistent victim, there was also at least one victim on the decreasing trajectory (details available from first author), underlining that within-group differences—individual characteristics—are important for persistent victimization.

Given the lack of a persistent-victims group in our control sample, we cannot say with certainty whether differences between persistent and decreasing groups indeed result from the intervention. However, we found that the trajectory groups did not differ in their victimization histories preceding the data collection as assessed at T1 (details available from first author). This lends support to the assumption that changes in victimization over time were due to KiVa.

The group-based trajectory approach assumes a finite number of distinct, developmentally homogeneous trajectory groups, but it cannot be determined with certainty whether these different groups exist in reality or whether they are a statistical artifact (Skardhamar 2010). That is, although latent classes may reflect qualitatively different meaningful real-world population subgroups, the distribution of true scores could also be continuous, and subgroups merely quantitatively different. Further, it can be difficult to arrive at a definite solution concerning the number of trajectories. That said, our solutions were not only supported by the fit indices but were also theoretically meaningful.

Some of our findings raised questions that went beyond the scope of this study, such as whether the effect of parent-child relationship quality indeed predicts persistent victimization through its effect on children’s behaviors towards and interactions with peers. Findings from indirect effect models are needed to shed light on these mechanisms. In addition, risk characteristics do not operate in isolation, but interact with each other in their effects on victimization. To get a more comprehensive view of the contexts in which risk characteristics are particularly harmful, interactions between risk characteristics in their effects on victimization need to be examined in future research.

The findings of this study have implications for anti-bullying interventions. The existence of persistent victims shows that even during an otherwise effective intervention, children can be victimized for a prolonged period. To prevent persistency, teachers need tools to recognize victims earlier and systematically tackle existing cases of victimization. In addition, interventions may also benefit from strategies to decrease victimization for particularly vulnerable children by improving peer dynamics more generally and including tailored strategies to stimulate social integration of rejected, anxious, or withdrawn children or those with a problematic family context. Such strategies could focus on safe interactions between these children and prosocial peers, to create bonds that increase resilience to peer victimization and to socio-emotional problems (Reijntjes et al. 2010). Further, they could tackle children’s potential interpretation bias, adapting effective strategies from methods based on social information processing models, such as positive interpretation modification training. Finally, interventions may benefit from a parental component to broaden the scope of the intervention, such as including parent-teacher meetings and actively involving parents (Ttofi and Farrington 2011).