Here is the design of a clinical trial:

Official Title: Interactive Malaysian Childhood Healthy Lifestyle Program (i-MaCHeL) Intervention for Preschool's Child-parent Dyads to Prevent Childhood Obesity: A Cluster-randomized Controlled Trial

Included conditions:
- Childhood Obesity Prevention

Study Armgroups:
- {'label': 'Interactive Malaysian Childhood Healthy Lifestyle Program (i-MaCHeL)', 'type': 'EXPERIMENTAL', 'description': 'The preschool children in the experimental group will be exposed to interactive classroom instruction, and their parents will be exposed to the Web-based program. In the experimental group, apart from the standard preschool health education curriculum, the preschool children will also be exposed to the interactive activities and quizzes using Web 2.0 tools, educational videos of a healthy lifestyle, sensory-based food education activities, cooking demonstrations, fun, and active games, and exercises. Whereas the parents will be exposed to Web-based healthy lifestyle educational materials, videos, and pictures sharing, quizzes, and communication through the WhatsApp and closed Facebook groups. Besides, a total of 3 messages per week will be delivered to the parents in the experimental group. The messages will be included announcing the release of a new topic, a reminder to log in to the website and read the health information, and a reminder to participate in the online activities.', 'interventionNames': ['Behavioral: Experimental Group: Interactive Malaysian Childhood Healthy Lifestyle Program (i-MaCHeL)']}
- {'label': 'Standard health education', 'type': 'ACTIVE_COMPARATOR', 'description': 'The children in the control group do not have exposed to the i-MaCHeL interactive classroom instruction, and their parents do not have access to the i-MaCHeL website materials. Thus, the children will be continued with standard health education only in the preschool setting, and their parents will be received Web-based health newsletters. The Web-based newsletters consist of general health information that are relevant to the preschool life stage. In ensuring that the experimental and control groups appear the same, the topics in the Web-based newsletters will have a look and feel similar nature to the experimental group condition. But still, the topics will not be included the interactive components such as videos and pictures sharing activities, quizzes, individualized feedback, and communication through WhatsApp and closed Facebook groups. Only one message (announcement of the release of a new topic) per week will be delivered to parents of the control group.', 'interventionNames': ['Behavioral: Control Group: Standard health education']}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'Experimental Group: Interactive Malaysian Childhood Healthy Lifestyle Program (i-MaCHeL)', 'description': 'The preschool children in the experimental group will be received the i-MaCHeL program delivers through interactive classroom instruction, and their parents will have access to the i-MaCHeL Web-based program.', 'armGroupLabels': ['Interactive Malaysian Childhood Healthy Lifestyle Program (i-MaCHeL)']}
- {'type': 'BEHAVIORAL', 'name': 'Control Group: Standard health education', 'description': 'The children in the control group will be continued with standard health education only in the preschool setting, and their parents will be received general Web-based health newsletters.', 'armGroupLabels': ['Standard health education']}

Primary Outcomes:
- {'measure': 'Changes in child BMI-for-age z-score', 'description': 'Anthropometric measurements such as body weight and height will be assessed according to the standard procedures of the World Health Organization (1995). BMI will be calculated using the standard formula (kg/m2). BMI-for-age Z-score curve, according to the WHO references will be used to classify weight status. The child weight status will be categorized into four categories which are overweight (\\> +1SD of BMI-for-age z-score), obese (\\> +2SD of BMI-for-age z-score), thinness/wasting (\\< -2SD of BMI-for-age z score) and normal weight (+1SD to -2SD of BMI-for-age z-score).', 'timeFrame': '3-month and 9-month after baseline'}

Please estimate the sample size based on the assumption: 
The study assumes an 80% power to detect a small to medium effect size at a 5% significance level. The design effect due to cluster sampling is 1.37, and a 20% loss to follow-up is anticipated.
Sample size
        The sample size is calculated for the primary outcome, BMI z-score. The sample size for individual randomisation of the present study is based on Formula 1 [29]. The values used in the sample size calculation are based on the BMI z-score data from Ahmad et al. (2018) [30] study, which is 1.95Â±0.45 and 2.09Â±0.35 for the treatment and control groups, respectively. Based on Formula 1, a calculated sample size required for each group arm is 131 child-parent dyads. It is calculated that, with at least 80% power to identify a small to medium effect size [31] at the 5% significance level, the present study needs a total of 262 child-parent dyads for the two-group arm.

nIndividual_Binary=(z1âÎ±2+z1âÎ²)2[Ïtrt2+Ïcon2r]Î2
(1)

where, r=nconÏcon,Î=Î¼trtâÎ¼con
        Î¼trt = Mean in treatment group = 1.95
        Î¼con = Mean in control group = 2.09
        Ïtrt = SD. in treatment group = 0.45
        Ïcon = SD. in control group = 0.35
        z = Critical z value for a given Alpa (Î±) = 0.05 (two â sided) and Beta (Î²) = 0.2 with the value of z1âÎ±2 = 1.96 and z1âÎ² = 0.84
        r = Ratio of the two sample sizes = 1/1
        An adjustment using the design effect (DE) is made for the calculated sample size to allow for the design structure (due to the cluster sampling method), which results in larger sample sizes [32]. Taking into account unequal cluster size [10], assume the mean cluster size of 38 child-parent dyads will be recruited per preschool. Based on the Formula 2 [32, 33], given that the number of individuals per cluster (n) in the present study is 38 child-parent dyads and the Intra-cluster correlation coefficient (Ï) from the previous studies is 0.01 [18, 34], the calculated design effect of the present study is 1.37.
        
Designeffect(DE)=1+(nâ1)Ï
(2)

        By considering the design effect is 1.37 and the sample size required for each group arm (nIndividual_Binary) is 131 (see Formula 3), the total sample size of the individual randomisation is further increased from 262 to 360 child-parent dyads.
        
(nIndividual_Binary)ÃDesigneffectÃ2
(3)

        After estimating a loss to follow-up of 20% for this trial, the final sample size is increased to a total of 460 child-parent dyads (230 per group arm). Thus, based on the total number of participants in the two groups is 460 and the number of individuals per cluster is 38 child-parent dyads (see Formula 4), a calculated number of preschool clusters in the present study is 12 preschools. Therefore, 6 preschool clusters will be randomised to each experimental and control group.
        
n_cluster=Totalnumberofparticipantsinthetwogroupsnumberofindividualspercluster
(4)