Test a Post-Creation Tab While Accounting for User Interference

A question-and-answer platform is considering adding a post-creation tab next to its existing question tab. Design a test to determine whether this is a good idea, from defining the hypothesis through analysis and a launch recommendation. Address interference: content created by treated users may be read or interacted with by control users, so one user's treatment can affect another user's outcome.

Clarify what the new post format allows and what success means before choosing an outcome. No traffic volume, network structure, experiment duration or effect size is supplied. Explain how you would select a randomization unit and comparison strategy, estimate the necessary sample or duration, and interpret the results when spillovers cannot be eliminated completely.