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Field Before After
Trial Status in_development on_going
Trial End Date November 07, 2022 January 06, 2023
Last Published November 04, 2022 05:40 PM November 07, 2022 10:18 PM
Intervention End Date November 07, 2022 November 08, 2022
Randomization Method Randomization done by Qualtrics. We use a block randomization method which is achieved by the randomizer function embedded in Qualtrics. Among the 1,200 participants recruited, 600 will be randomly assigned to the control group, and the other 600 will be randomly assigned to the treatment group. Randomization done by Qualtrics. We use a block randomization method which is achieved by the randomizer function embedded in Qualtrics. Among the 1,600 participants recruited, 800 will be randomly assigned to the control group, and the other 800 will be randomly assigned to the treatment group.
Planned Number of Observations 1,200 US citizens who are over 18 years old 1,800 US citizens who are over 18 years old
Sample size (or number of clusters) by treatment arms 600 participants in the control, 600 participants in the treatment group. 800 participants in the control, 800 participants in the treatment group.
Power calculation: Minimum Detectable Effect Size for Main Outcomes According to our previous experiment data (the experiment was pre-registered on AEA RCT registry, doi: https://doi.org/10.1257/rct.7070), to observe a change of 20% standard deviation (sd = 26), power of 0.8, and alpha of 0.05 (two-sided), we need a minimum detectable effect size of around 400. Assuming a 70% retention rate in our two-stage study, we need the minimum detectable effect size to be 571. According to our previous experiment data (the experiment was pre-registered on AEA RCT registry, doi: https://doi.org/10.1257/rct.7070), to observe a change of 20% standard deviation (sd = 26), power of 0.8, and alpha of 0.05 (two-sided), we need a minimum detectable effect size of around 400. Assuming a 50% compliance rate of encouragement in our two-stage study, we need the minimum detectable effect size to be 800 per group.
Pi as first author No Yes
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