Sample size (or number of clusters) by treatment arms
250 users in control
250 users for Treatment 1
250 users for Treatment 2
50 grids with 5 users and total of 250 users each in control, treatment 1, and treatment 2
Power calculation: Minimum Detectable Effect Size for Main Outcomes
We carried out power calculations for our primary outcome, using the mean and standard deviation of the probability of correctly identifying a news as true or false, observed in the pilot data. Our calculations show that with a cluster randomized design, and user level outcomes measured at baseline and endline, assuming a significance level of 5\%, 80\% power, cluster size of 5, and intra-class correlation of 0.05, and 50 grids per arm, it will be possible to detect a standardized effect of 0.30. This amounts to a 23\% increase in the mean of the primary outcome from 0.63 to 0.77 (standard deviation 0.48). We expect to gain statistical power as we will measure and control for user's baseline score in correctly identifying news as well as user's baseline characteristics.