Before revision:  Our contributions are to formalize the problem, find the theoretically optimal revenue attribution scheme for anyreasonable conversion value scheme and show empirical results on past data of a free-to-play mobile game using different conversion value schemas.
After revision:  Our contributions are to formalize the problem, find the theoretically optimal revenue attribution scheme for anyreasonable function for any conversion value schema, and show empirical results on past data of a free-to-play mobile game using different conversion value schemas.