Here is the design of a clinical trial:

Official Title: Testing FIRST in Youth Outpatient Psychotherapy

Included conditions:
- Anxiety
- Depression
- Trauma
- Behavior Problem

Study Armgroups:
- {'label': 'FIRST', 'type': 'EXPERIMENTAL', 'description': 'FIRST is built upon five empirically supported principles of change (ESPCs-i.e., feeling calm, increasing motivation, repairing thoughts, solving problems, trying the opposite). Each principle can be applied to treatment of problems spanning depression, anxiety (including OCD and PTS), and conduct problems-thus encompassing a majority of the youths seen in outpatient care. Its design addresses breadth of problem coverage, youth comorbidity, and flux in youth treatment needs during episodes of care. It is used in conjunction with performance feedback via a web-based tracking system that gives clinicians weekly data on youth treatment response. FIRST has treatment and training efficiency, and efficient clinician skill-building is supported by group consultation.', 'interventionNames': ['Behavioral: FIRST']}
- {'label': 'Usual Care', 'type': 'ACTIVE_COMPARATOR', 'description': 'Treatment in the usual care (UC) condition will use the clinical procedures therapists consider appropriate and believe to be effective.', 'interventionNames': ['Behavioral: Usual Care']}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'FIRST', 'description': 'FIRST is built upon five empirically supported principles of change (ESPCs-i.e., feeling calm, increasing motivation, repairing thoughts, solving problems, trying the opposite). Each principle can be applied to treatment of problems spanning depression, anxiety (including OCD and PTS), and conduct problems-thus encompassing a majority of the youths seen in outpatient care. Its design addresses breadth of problem coverage, youth comorbidity, and flux in youth treatment needs during episodes of care. It is used in conjunction with performance feedback via a web-based tracking system that gives clinicians weekly data on youth treatment response. FIRST has treatment and training efficiency, and efficient clinician skill-building is supported by group consultation.', 'armGroupLabels': ['FIRST']}
- {'type': 'BEHAVIORAL', 'name': 'Usual Care', 'description': 'Treatment in the usual care (UC) condition will use the clinical procedures therapists consider appropriate and believe to be effective.', 'armGroupLabels': ['Usual Care']}

Primary Outcomes:
- {'measure': 'Child Behavior Checklist (CBCL; Achenbach & Rescorla, 2001) and Youth Self-Report (YSR; Achenbach & Rescorla, 2001)', 'description': 'The CBCL is a parent-report checklist with 113 youth problem items, each rated on a 0-1-2 scale (0 = not true, 1 = somewhat/sometimes true, 2 = very often true). The YSR is a corresponding 112-item youth-report checklist measure. From both the CBCL and the YSR, T-scores, adjusted for age and gender, Internalizing, Externalizing, and Total Problems scales will be used for outcome assessment. Higher scores represent more severe problems, with borderline and clinical cutoffs at T = 60 and T = 63, respectively. Evidence of CBCL/YSR validity and reliability is strong and extensive.', 'timeFrame': 'Change from baseline to 18 months (quarterly at 0, 3, 6, 9, 12, and 18 months from 0 up to 78 weeks)'}
- {'measure': 'Behavior and Feelings Survey (BFS; Weisz et al., 2020)', 'description': 'The 12-item BFS is a measure of internalizing (6 items), externalizing (6 items), and total problems, developed via four studies, three with samples of clinically referred youths aged 7-15 and their caregivers. Both youth and caregiver forms showed robust factor structure, internal consistency, test-retest reliability, convergent and discriminant validity in relation to three well-established symptom measures (including CBCL and YSR), and slopes of change indicating efficacy in monitoring treatment progress during therapy. Items are rated on a scale from 0 (not a problem) to 4 (a very big problem). Internalizing and externalizing scale scores range from 0 to 24 and total problems from 0 to 48 (with higher scores indicating greater problem severity).', 'timeFrame': 'Change from baseline through end of treatment (weekly from 0 up to 78 weeks)'}
- {'measure': 'Functional Top Problems Assessment (TPA; Weisz et al., 2011)', 'description': 'The TPA assesses youth and caregiver severity ratings (from 0 = not a problem to 4 = a very big problem) for the functional top three problems the youth and caregiver independently identified as most important to them, in separate baseline interviews. Psychometric analyses have shown strong test-retest reliability, convergent and discriminant validity for the TPA in relation to standardized measures, and sensitivity to change during treatment.', 'timeFrame': 'Change from baseline through end of treatment (weekly from 0 up to 78 weeks)'}

Please estimate the sample size based on the assumption: 
The assumptions include an ICC of 0.02, 5 out of 6 repeated measures, a significance level (α) of 0.05, power (1-β) of 0.80, and a conservative attrition/data loss rate of 15%.
Sample size and power
        The target sample size is Nâ=â212 youths. We used Optimal Design [59] to determine power for the main treatment effects, specifically comparing the rate of change for FIRST vs. UC. Assuming at least 24 providers, an ICC of 0.02 (based on prior RCETs), 5 of 6 repeated measures (quarterly schedule, anticipating some missing data), and standard thresholds for significance (Î±â=â0.05), we determined that a minimum sample of Nâ=â180 youth participants was required to achieve adequate power (1-Î²â=â0.80) to detect an effect size (ES) of 0.50 This ES of 0.50 or higher is anticipated for two specific primary outcomes measuresâthe CBCL [30] collected quarterly and the parent-rated TPA [33] collected weekly. As a transdiagnostic intervention trial covering multiple problem areas and a wide developmental range, broad composite measures are most appropriate as the basis for power estimation. Further, caregivers are considered the primary informants due to higher reliability and validity of caregiver report across all youth ages [30, 33, 60]. The selection of the ES magnitude (e.g., 0.50) was based on synthesizing evidence from three previous open trials of FIRST [8] which ranged from 0.45 to 0.98 and randomized trial research with MATCH [15, 16, 61] which ranged from 0.29 to 0.72. The data for MATCH showed an average ES reduction of 43%. When applied to the FIRST findings, the results predicted an ES of 0.51 for FIRST compared to usual care, thus our ESâ=â0.50 hypothesis. The estimation of an ES of 0.50 strikes an appropriate balance between Type I and Type II errors, and between cost-effectiveness and scientific assuredness. Further, we anticipate a conservative attrition/data loss rate of 15% will occur between allocation and analyses. Thus, a target sample size of Nâ=â212 youths will ensure adequate power for the primary analyses (Aim 1).
        Monte Carlo simulations were conducted in R using the simsem package [62] to estimate power for the Aim 2 mediation analyses. These simulations revealed that 180 participants will provide sufficient power to detect whether FIRST can produce a 0.36-SD change in the slope of the CBCL/YSR symptom improvement through the indirect effect of change in negative affect regulation.
        Analyses of variables that may be associated with EST implementation (Aim 3) are considered exploratory and therefore were not designed to be adequately powered. Further, available power will vary across models. Nonetheless, power for these models was simulated using the simr package in R [63] which found a sample size of 180 to be adequate to detect a standardized regression coefficient as low as 0.25 for clinician-level predictors/moderators of outcomes within the FIRST condition (anticipatingâ~â90 youths across 12â20 FIRST clinicians).