Here is the design of a clinical trial:

Official Title: Mental Health Prevention Among Preschool Children: a Pilot Study of the Adaptation of the I Can Problem Solve (ICPS) Program to Chile

Included conditions:
- Mental Health
- Aggressive Childhood Behavior
- Problem Behavior
- Social Behavior

Study Armgroups:
- {'label': 'ICPS with internal school facilitator', 'type': 'EXPERIMENTAL', 'description': 'Schools with preschool students. All consented students in the class will participate in the ICPS preschool program, adapted to the Chilean reality and culture. The program is manualized and will be delivered by the early educator of the class, who is part of the school personnel.This internal facilitator will be trained in the program. Each of the 59 sessions lasts around 20 minutes, delivered 2 to 3 times a week, during 5 months. ICPS content includes vocabulary and concepts about emotions, and the development of problem-solving skills, practising alternative solutions, consequences and the sequential thought (solutions-consequences). Interactive techniques (e.g. games, role-playing, and the use of stories, illustrations and puppets), and guided discussion strategies are used to solve problems.', 'interventionNames': ['Behavioral: I Can Problem Solve (ICPS) Program']}
- {'label': 'ICPS with external facilitator', 'type': 'ACTIVE_COMPARATOR', 'description': 'Schools with preschool students. All consented students in the class will participate in the ICPS preschool program, adapted to the Chilean reality and culture. The program is manualized and will be delivered by an external trained early educator, who is part of the research team. The early educator of the class, who is part of the school personnel, will also be trained to collaborate with all the program activities with the external facilitator. Each of the 59 sessions lasts around 20 minutes, delivered 2 to 3 times a week, during 5 months. ICPS content includes vocabulary and concepts about emotions, and the development of problem-solving skills, practising alternative solutions, consequences and the sequential thought (solutions-consequences). Interactive techniques (e.g. games, role-playing, and the use of stories, illustrations and puppets), and guided discussion strategies are used to solve problems.', 'interventionNames': ['Behavioral: I Can Problem Solve (ICPS) Program']}
- {'label': 'Control Group', 'type': 'NO_INTERVENTION', 'description': 'School in the control group will continue to carry out their normal academic and prevention activities.'}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'I Can Problem Solve (ICPS) Program', 'description': 'The 59 sessions of ICPS program explicitly promote cognitive regulation, solving social problems, and emotional learning skills.', 'armGroupLabels': ['ICPS with external facilitator', 'ICPS with internal school facilitator'], 'otherNames': ['Interpersonal Cognitive Problem Solving Program']}

Primary Outcomes:
- {'measure': 'Acceptability', 'description': 'Acceptability of the intervention will be assessed using qualitative questionnaires', 'timeFrame': '5 months'}
- {'measure': 'Feasibility', 'description': 'Feasibility will be assessed by looking at the number of students successfully completing the study', 'timeFrame': '5 months'}
- {'measure': 'Parental report of psychological difficulties', 'description': 'The psychological difficulties will be assessed using the total subscale of difficulties of the Parents version of The Strengths and Difficulties Questionnaire (SDQ)', 'timeFrame': '8 months'}
- {'measure': 'Parental report of psychological strengths', 'description': 'The psychological strengths will be assessed using the total subscale of difficulties of the Parents version of The Strengths and Difficulties Questionnaire (SDQ)', 'timeFrame': '8 months'}

Please estimate the sample size based on the assumption: 
A two-sided contrast analysis with a 20% loss to follow-up rate is assumed. Despite evidence supporting a one-sided analysis, a two-sided analysis is chosen to align with common practices in randomized controlled trials.
Sample size
        Since this is a pilot study, it is not appropriate to calculate a sample size for establishing the effectiveness of the intervention [45]. However, we have calculated a suitable number of children for this study. According to some studies, we expect that the proportion of children who will have disruptive symptoms within 1âyear in the waiting-list control group will be 30%, compared to 10% for those children in any of the intervention arms. For a loss to follow-up calculated at 20% and in a two-sided contrast analysis, 75 children will be required per arm and 225 children in total. Despite evidence to support a one-sided analysis for this case, since we assume that the intervention will not cause harm, we will conduct a two-sided analysis as is common in randomised controlled trials. This number is adequate according to recommendations for feasibility studies that propose a minimum of 30 participants per arm to estimate the parameters for future sample size calculations [46]. We have considered the selection of 12 educational institutions as an adequate size for this pilot study, with three arms: four schools in the control group and four in each of the two intervention groups. In one of the intervention groups, the ICPS programme facilitator will be the preschool educator of the educational establishment itself, while in the other group, the facilitator will be an external preschool educator hired by the research team. Since each of these educational institutions meet the aforementioned inclusion criteria, they may be considered to have similar characteristics. An average participation of 20 students is desired per course, so we hope to recruit a total of 20 students per school. Each arm of the study should have a total of 80 students for a total of 240 students, just above the expected sample size calculated.