Statistical Analysis Plan
The significance threshold was α=.05 throughout. Before planning the analysis, a chi-square test was conducted to compare baseline main mental health problem between the 2 trials. There was a significant difference (For objective 1, demographic and clinical characteristics of participants randomized to each trial were described via means and SDs or medians and IQRs for normally distributed and nonparametric continuous data, respectively. Categorical data were described through counts with percentages. Descriptive statistics were calculated for all baseline demographic items and for the index scores for all measures. Ethnicity responses were grouped into 2 categories (White British and Other ethnicity) because of the small numbers of participants in most ethnicity categories and because minority identities historically predict mental health problems, mediated by minority stress [For objective 2, demographic information on service use was used to partition trial participants into 1 of 2 disjoint categories. For objective 3, responses to Q8 were used to partition NEON Trial participants in the Following UK Data Service guidance on statistical disclosure [