Analysis Plan
To evaluate the effect of engagement with different types of tailored behavioral content, a hierarchical mixed model approach was used. Specifically, model 1 tested the effects of total log-in duration; total number of sessions completed (0-8); and covariates, including baseline MVPA, baseline BMI, demographics (income, sex, and age), time-related variables for PA (weekend and season), and a dummy code for the face-to-face group-based treatment (0=control and 1=intervention). Model 2 added engagement with the PA content session (log-in status and duration). Model 3 added engagement with the sedentary behavior session, and model 4 added engagement with the energy balance session. Finally, model 5 included diet-focused content sessions, including the fruits and vegetables, sweetened beverages, and fast food sessions. The log-in status for each content session was a dummy-coded variable (0=no log-in and 1=log-in), and the log-in duration was a continuous variable. In addition, to account for nesting within treatment groups during the face-to-face phase of the program, the mixed modeling approach included a random effect for group-based treatment. Likelihood ratio tests were used to compare the models.To aid in interpreting the results, all continuous variables were mean centered, including covariates and predictors. Before analysis, outliers for the log-in duration were recoded to reflect a maximum of 3 times the IQR using a winsorizing approach [