Bullying generally characterised by the imbalance of power perception between a student who is bullied and a student who is bullying others. It could be not an imbalance of power but an imbalance of power perception. Uncovering this possible power imbalance formation might be a sound way to understand the harm of bullying and reveal the roles of students in bullying (Horton et al., 2022). These roles are identified as bully, victim, bully-victim, and bystander in the bullying literature. The bystander students are generally the most significant number in schools (Bauman et al., 2020). Bystanders know about bullying that is happening to someone else (Macaulay et al., 2024). Bystanders are three types. The first one is the reinforcer, the second one is the defender, and the third one is the passive bystander (Sarmiento et al., 2019). Bystanders are of prime importance to change school climate to bullying-free. Bystanders-based bullying prevention programs are effective and helpful to protect students from the effects of bullying (Abraczinskas et al., 2022; Bauman et al., 2020).

Peer support and advocacy have been commonly used in bullying prevention programs and strategies. Peer support prevents bullying from remaining hidden. It is an effective tool to reveal bullying in peer bullying prevention programs, especially with advocacy. It also helps the victim feel safe (Bracci et al., 2019; Sekar & Fauzia, 2023). Peer advocacy is a strategy for students where peer support can be performed by students (Abraczinskas et al., 2022). In the last two decades, peer advocacy programs and strategies have many barriers. The main barriers are the high cost, time deficiencies, and intensive workforce. Bullying prevention programs need to be ergonomic, short, understandable, and applicable to students (Bracci et al., 2019; Midgett et al., 2015). Midgett and colleagues developed four basic strategies (STAC) to use for peer advocacy. STAC fulfils expectations of bullying prevention programs in the current literature. STAC is comprised of the combination of the initial letters for the following four basic strategies. The first strategy is Stealing the show. The second strategy is Turning it over. The third strategy is to Accompany others. The last strategy is Coaching compassion (Midgett et al., 2015, 2017a).

STAC strategies were developed to reduce or prevent bullying in schools. Preventing bullying is more effective and less stressful than coping with complex issues that may occur after bullying behaviours. STAC strategies support bystander students to act as advocates when they encounter a bullying episode. Many bystander students often remain passive when they encounter bullying because they generally do not know what they need to do or say. The school health team, especially nurses, should inform these bystander students about the negative consequences of being passive and how to intervene in a positive manner (Bauman et al., 2020; Midgett et al., 2015, 2017a). If bystander students encourage bullies, bullying might increase. On the other hand, if bystander students help victims defend themselves, bullying might decrease (Jenkins et al., 2022). STAC strategies were developed to implementation process as a teaching technique. In this research, STAC, which only determines the content of the implementation, was not sufficient (Midgett et al., 2015, 2017a). Logic Model was needed to structure the content of the education program and ABCD model was needed to standardize the aims and objectives of the education sessions.

ABCD model is a good guideline designing objectives. In this education plan, ABCD model is used to writing the session aims and objectives. Objectives are the most important part of education because education should be observable and measurable, unambiguous, clearly written. Also, it should be specific for the education process. There are two-level objectives. They are described as enabling (first level) and terminal (second level). Terminal objectives identify the overall goal of the instruction for the education program. They are enabling objectives to identify the goals of each session. ABCD model includes four components as audience, behaviour, condition and degree. Audience describes potential participants. It gives information about a person who is to exhibit the performance. Behaviour describes student capability or skill. Skills should be measurable or observable. Skills might be written in the four domains of learning as cognitive, psychomotor, affective, or interpersonal. It gives information about visible performance is the learner to their exhibit. Audience and behaviour are identified in the first level objectives. The condition describes environmental conditions, equipment or tools. It gives information about conditions are provided for the learner at the time of evaluation. Degree describes the time, accuracy, proportion and quality as a standard for acceptability. It gives information about how constitutes a minimum acceptable response from participants (Mager, 1997; Wildschut, 2014).

Logic Model is a kind of process tool that program managers and evaluators to describe the effectiveness of their programs. In this education program, the Logic model used for programme evaluation. In the Logic model programme evaluation is the description that the logical linkages among inputs (intentional transformation of specific resources), activities (process), outputs (desired outcomes), and results (short term and long term). In this study, we used the Logic model three-component as a resource, activities, and results. In other words, the Logic model is a provided framework. Logic model is a kind of tool that can be used to unpack hypothesis to understand the assumptions and create strategies to test the hypothesis (Schiffman et al., 2019; Olsson et al., 2023).

School health teams are inter-professional, such as teachers, social workers, general practitioners, nurses and other health professionals. They are expected to exhibit an unbiased and positive perspective when interacting with students (Watson et al., 2022; Kvarme et al., 2020; Sabry et al., 2021). Nurses have important roles in preventing bullying by being educators, counsellors, or advocates (Seyhan Şahin & Ayaz-Alkaya, 2024). With the help of these roles, nurses can systematically approach students to prevent bullying and support school health team members (Kvarme et al., 2020; Sabry et al., 2021). School nurses can support the school health team by observing and intervening with younger students before they start risky life behaviours (Forbes et al., 2019). School nurses have an active role as a member of the school health team in carrying out school health services (Kvarme et al., 2020). Peer relations and friendship might impact the bullying process and students role in bullying. Students who have good friendship quality and are popular among their friends experience negative behaviors such as bullying less frequently (Lo Cricchio et al., 2023). In a study, especially for male students, friendship qualities were found to be both a negative factor and a positive preventive factor. In the same study, it was suggested that friend relationships should also be questioned in bullying prevention programs (Cao et al., 2023).

STAC strategies are an evidence-based practice that has been used in the United States. Peer bullying spreads fast; we're out of time (Midgett & Doumas, 2016; Moran et al., 2019). Evidence-based practices should be expanded. The rationale role of this current study makes a prelude to expanding this practice. Also, there is a difference of this study. We used STAC with two more models. Any studies that have utilised STAC outside the United States are lacking in the literature. This study is the example of Wales. It could be the beginning of the other countries. This research was conducted to evaluate the effect of STAC strategies on bullying prevention through peer advocacy among sixth-grade students in Wales.

Hypotheses

  • H0-a: There is no difference between groups regarding student advocacy in bullying.

  • H0-b: There is no difference between groups regarding bullying knowledge.

  • H0-c: There is no difference between groups regarding STAC knowledge.

  • H0-d: There is no difference between groups regarding self-confidence to intervene to stop the bullying.

Methods

Study design and setting (resources of logic model)

The study was conducted as a quasi-experimental design with pre and post-tests in the fall term of the 2019–2020 school year. The population of the study consisted of sixth-grade students in four primary schools in Wales, the United Kingdom. Headteachers and teachers designated the first school (N:19, n:10) and the second school (N:28, n:28) as control groups. Similarly, the third school (N:17, n:14), and the fourth school (N:24, n:24) were designated as intervention groups. Each school has one sixth-grade class, and education was conducted in the classroom. Students’ chairs were arranged as four or three chairs per group for suitable group activities (Table 1).

Table 1 Education program
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Participants and educator (resources of logic model)

Total population sampling, which is a purposive sampling technique, was used in this study. All sixth-grade students who volunteered and had their parents' permission were included in the study sample (n(intervention) = 38, n(control) = 38). According to power analysis, the required sample size for each group is at least 26 students to obtain 80% power for a 95% confidence level. The sessions of education program were given by the first author, whose major is public health nursing. STAC was used as a school nursing intervention in this study. Each student could be a potential bystander role in bullying (Peck et al., 2024). Whether they are bullies, victims or in some other roles, all students in the school are considered as potential bystander in current study.

Data collection tools (resources of logic model)

Data were collected with a personal information form, the SAPPS, and the Friendship Qualities Scale. The personal information form consisted of eight closed-ended questions to determine the gender, parental education and working status, school achievement, and bullying experiences. Two questions about bullying experiences included bullying definition.

The SAPPS was developed by Midgett and colleagues (Midgett et al., 2015) to evaluate the effectiveness of STAC education. It is evaluated by students’ knowledge of bullying (items 1, 4, 7, 10), STAC strategies knowledge (items 2, 5, 8, 11), and self-confidence to intervene to stop bullying (items 3, 6, 9). This scale consists of 11 items. Scale responses are scored as 1 “completely disagree,” 2 “disagree,” 3 “agree,” and 4 “completely agree.” The highest total score that can be obtained from the scale is 44, and the lowest score is 11. According to a scale score evaluation—as the total score of the scale increases, the effectiveness of STAC education increases. Total Cronbach’s alpha was 0.77 (Midgett et al., 2015). In this paper, all items are loaded onto a single factor, with good internal consistency (n = 78, Cronbach Alpha = 0.85, with pre-test).

The Friendship Quality Scale was developed by Bukowski et al. (1994) to evaluate the quality of friendship relationships with the close friends of the adolescent. The five-point Likert scale consists of 23 items. The scale items are scored as 1 “not true,” 2 “rarely true,” “sometimes correct,” 4 “quite accurate,” and 5 “very accurate.” The students are asked to answer the scale items considering their close friends. An increase of total score indicates that the quality of peer relations is increased. In this paper, all items were loaded onto a single factor with good internal consistency (n = 78, Cronbach Alpha = 0.84, with pre-test).

Research procedure (activities of logic model and STAC strategies)

The research was conducted between September and November 2019. The STAC education schedule was created by school managers and the researcher. Before the study intervention, informed consents and assents were received from parents and students. The study was not blinded—students had information about the study process because of the volunteering. The data collection tools (as a pre-test) were administered to the sixth-grade students in the four schools. The STAC education program was conducted in the two intervention groups. The STAC intervention consisted of one group education (60 min) and two group meetings (each meeting, 30 min). Sessions were held once a week.

The researcher conducted the sessions in small groups. Each group had three or four students. The sessions were arranged on the same days to ensure both intervention schools' similarity (equal). After the intervention, the same tools (as a post-test) were re-applied to the sixth-grade students in the four schools. After the post-tests, brochures about bullying were distributed to students in the control groups. A group education (60 min) was arranged for those in the control group who requested education. The education was similar to the intervention groups’ education.

Education program (activities of logic model, STAC strategies, ABCD model)

The education program included STAC strategies and was comprised of three sessions which were given to the intervention group. STAC consists of the first letter of the following word groups: “stealing the show,” “turning it over,” “accompanying others,” and “coaching compassion.” The education content is based on the Logic Model and ABCD Model. The Logic Model was used for program evaluation. This model is the description of the logical linkages among resources, activities, outputs, and results (Schiffman et al., 2019). The ABCD model was used to write the objectives for the sessions. The ABCD model includes four components: audience, behaviour, condition, and degree. The audience describes students in this study. Each session objective covered these four components in the ABCD Model (Mager, 1997). Also, the ABCD model helps to standardize education guidelines. Model-based bullying education programs are more effective than others (Evgin & Bayat, 2020). ABCD took part in all prevention program ingredients and processes in the current education guidelines. In other words, program expectations were structured according to the ABCD model (Table 4).

Statistical analysis (results of logic model)

Data were analysed by using the IBM SPSS Statistics version 20.0. Percentage, mean, number and standard deviation were used for descriptive analyses. The significance level was accepted as p < 0.05 in all statistical procedures. There were no missing data. For evaluating the normality of the data distribution, the Skewness and Kurtosis values were used. The chi-square test was used for categorical variables. An independent t-test was used for intergroup comparisons and dependent groups. Paired samples t-test was used for in-group comparisons. The graphics of effect size and comparison between groups were made using the repeated measures ANOVA.

Results

The percentage of girls was 55.3% in the intervention group and 47.4% in the control group. School success perception of students was good in the intervention (44.7%) and control (52.6%) groups. In the intervention group, 15.8% of students have bullied others (reinforcer bystander), and 26.3% of students have been bullied (passive bystander), Similarly, in the control group, 23.7% of students have bullied others (reinforcer bystander), and 36.8% of students have been bullied (passive bystander) (Table 2). Also, among all participants, students who bullied others were 19.7%, and students who had perpetrated bullying were 31.6%. All students in the intervention and control groups were know or aware of bullying at school.

Table 2 Descriptive and bullying characteristics of students
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According to the post-test of the independent samples t-test, the SAPPS mean score was found to be statistically significant between groups (p = 0.011). Also, there was a significant difference of the Self-Confidence to Intervene to Stop Bullying sub-scale mean scores in the post-tests (p = 0.007) (Table 3). However, the other two sub-scales were found statistically insignificant between groups for the post-tests.

Table 3 Student’s pre-post test scores on the friendship qualities scale, SAPPS, and sub-groups
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Figure 1 shows the mean scores of SAPPS changing over time. The change in the intervention group was considerably higher than the change in the control group (Fig. 1).

Fig. 1
figure 1

Change of bullying student-advocate (SAPPS) over time. 1 = pre-test, 2 = post-test

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The mean scores of the SAPPS showed that the time × group interaction effect was significant (F = 7.30, p = 0.01, pη2 = 0.09). Also, the time × group effect (F = 0.05, p = 0.81, pη2 = 0.07) in the mean score of the friendship qualities scale was not found significant (Table 4).

Table 4 Repeated measures ANOVA results of friendship qualities scale, bullying student-advocate scale, and sub-groups over time
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Discussion

Gender, perception of school success, and bullying experience characteristics were not statistically different between intervention and control groups (p > 0.05) (Table 2). Intervention and control groups are similar. According to the post-test of the independent samples t-test, the SAPPS mean score was found to be statistically significant between groups (p = 0.011). H0-a hypotheses were rejected. Also, there was a significant difference of the Self-Confidence to Intervene to Stop Bullying sub-scale mean scores in the post-tests (p = 0.007). Similarly, H0-d hypotheses were rejected. However, the other two sub-scales were found statistically insignificant between groups for the post-tests. H0-b and H0-c hypothesis was accepted (Fig. 2).

Fig. 2
figure 2

Change of friendship qualities over time. 1 = pre-test 2 = post-test

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Bullying is generally executed quite secretly among students, so the school health team might be unaware of bullying. The student who is the perpetrator of bullying has the talent to hide the bullying from the school health team (Midgett et al., 2015). Students might be witnessing bullying behaviours in the schoolyards, toilets, and classes more than members of the school health team (Dennehy et al., 2020; Haegele et al., 2020). For this reason, students who witness bullying should be encouraged to try to stop the bullying. School health teams should teach students how they can advocate positively through peer support education programs (Midgett et al., 2015). An essential finding of this study is that the SAPPS post-test scores in the intervention group significantly increased compared to the pre-test scores. This result shows that STAC education, which is one of the peer support strategies, is compelling. This effectiveness is thought to stem from the models-based education program, materials, and team-based activities used within the scope of the education program. Studies also showed that peer support strategies were effective (Midgett & Doumas, 2016; Midgett et al., 2017b). The difference in the current study is that we used the ABCD and LOGIC model while conducting STAC strategies. Also, our results might be affected by those models, as well. Many students know what the general meaning of bullying is, but they might be confused about differences in other rude behaviours (Farrell & Walser, 2019). Students might interfere correctly with a bullying episode when they learn more bullying information. Another important finding in this research revealed that the intervention group post-test scores of the knowledge of bullying sub-scale significantly increased in comparison with the pre-test scores. Midgett and Doumas (2016) also support this finding. Consistent with the results, it could be said that the present bystander education program was effective in increasing student bullying knowledge compared to the control groups. Studies focus on the importance of the nursing role in bullying knowledge improvement (Sabry et al., 2021; Schiffman et al., 2019).

The current study highlights the role of school nurses as the primary responsible for raising bullying awareness among adolescents. Bullying is one of the most complex problems in the school system. A comprehensive school health team intervention might have a more long-sighted effect on bullying prevention rather than putting the responsibility solely on the shoulders of school nurses.

STAC strategies support students' engagement in bullying prevention. Students' knowledge of STAC strategies is vital to be able to respond to bullying (Midgett & Doumas, 2016). The current study has one unanticipated finding. The mean STAC strategies knowledge scores of the students in the intervention and control groups were significantly increased after the education compared to the pre-tests. The reason for these results might be because of the Halo effect. According to the halo effect, the pre-test results could have affected the results of the post-test because the pre-test might cause conditioning in participants.

Students have many personal talents to intervene in bullying. Self-confidence plays a crucial role in self-defence when students have been exposed to bullying bullies. According to a study, self-esteem skills can be helpful in overcoming bullying (Xie & Su, 2022). On the other hand, sometimes high-level self-esteem might be why students suffer from bullying (Tilindienė et al., 2012). The current study results support the first paradigm above written. The post-test scores of the self-confidence to intervene to stop bullying sub-scale significantly decreased compared to the pre-test scores in the intervention group. According to another study, the STAC program effectively increased self-esteem among elementary students (Midgett et al., 2017b). From this point of interpretation, the education program might effectively increase self-esteem among sixth-grade students. Self-esteem is important for positive relationships (Xie & Su, 2022). In addition, for STAC strategies to be more effective, students should have leadership responsibility, and establish positive relationships with their peers (Midgett et al., 2015). Therefore, the friendship qualities of the students are essential. Friendship is an influential concept on peer advocacy processes. While studying the peer advocacy processes, we had to track friendship status and levels. In this study, friend quality was similar in the intervention and control groups.

For the time by group interaction, self-confidence to intervene to stop bullying and knowledge of bullying sub-scales mean comparisons indicated large effect sizes in this study. The bullying student-advocate scale and STAC strategies knowledge sub-scale had a medium effect size except for friendship qualities scale scores (Field, 2013). Midgett and Doumas (2016) support the current study's findings according to the bullying student-advocate scale.

Bystander training has been shown to be generally effective in bullying prevention (Abraczinskas et al., 2022; Bauman et al., 2020). The education program of this study was comprised of the STAC strategies using bystander training. Literature has supported the effectiveness of the STAC strategies by bystander students to prevent bullying (Midgett & Doumas, 2016; Midgett et al., 2017b; Moran et al., 2019). Bullying, which is a complex public health problem, needs more professional and team-based interventions.

School health teams have a responsibility to prevent bullying in the schools (Bauman et al., 2020; Forbes et al., 2019; Kvarme et al., 2020). Many bullying prevention interventions are conducted by school health teams to protect students from psychological problems such as suicidal ideation or attempted suicide (Lever et al., 2019). Collaboration between school health team members is supported and recommended for intervention effectiveness. Those collaborations are important for revealing bullying which students at the schools hide (Kvarme et al., 2020; Lever et al., 2019).

The school nurse can support the school health team in their role as educator, counsellor, and advocate in the STAC process to prevent bullying. Effective bullying intervention programs and strategies could be added to school-based intervention programs as evidence-based programs. Especially, school students are in the critical life period for developing behaviours and bullying prevention. The STAC strategies are an effective method for the sixth-grade student. This study also addresses age diversity. School nurses should use STAC strategies in other age groups to prevent bullying.

Limitations

As a data limitation, this study was performed without follow-up tests because of time restrictions. A generalisation of the study results to other settings or age groups is limited. Our one result shows that the answers of the control groups’ students might change via time, environmental conditions, and self-reporting biases. The possible cause of this might be the halo effect, which is one of the self-reporting biases. The Halo effect might be rooted in peers, teachers, and parents' behaviours rather than solely the questionnaires (Wetzel et al., 2016). Also, according to the STAC program literature, self-report questionnaires are a disadvantage, leading to biases, especially with elementary school students (Midgett et al., 2015).

Peer social support is regarded as immensely profitable to support victims and prevent bullying (Sekar & Fauzia, 2023). Friendship Qualities Scale evaluates the quality of friendship relationships with just close friends. In this study, there is no scale that measures the general social friend relationships. This situation limited the results of the study. The results could have been more comprehensive if the friendship relationship had been handled in a multidimensional way.

The current study observed the knowledge change in the impact of STAC education on students. However, it is unclear whether this education translated into practice when a bullying incident occurs at school.

Conclusions

Bystanders are not ignored to prevent bullying. Bullying is a universal problem that needs local consideration and global intervention. This study shows that peer support strategies and a bystander training program are effective. Peer support strategies and the bystander training program increased student advocacy regarding bullying, knowledge of bullying, STAC strategies knowledge, and self-confidence to intervene to stop bullying. The STAC strategies are adequate for the success of peer support strategies and bystander education programs. We used STAC with two other models. Those models might add richness to STAC.

This study shows that it needs more studies highlighting gaps in the literature about evidence-based bystander intervention. The first and fourth hypotheses were rejected. However, the second and third hypothesis were accepted. This is an addressed country diversity for the current study. This study showed that STAC strategies are influential among the UK national samples. It should be used in other countries for future studies. Bullying is a worthwhile subject to study. Students still need more help from the academic world with international studies. This paper calls researchers who study bullying to collaborate.

Future studies could examine the process of STAC strategies in practice to clarify whether this education translated into practice when a bullying incident occurs at school. A longitudinal or cohort studies are needed to determine this about STAC.

Key practitioner message

  • The most prominent finding of this study is that peer advocacy intervention on bystanders is an effective way to prevent bullying.

The uniqueness of this study is that its initiative is the implementation of strategies in a different country via supported other models by researchers from a third country.