In this paper, I examine duopoly with multi-services, where firms offer delivery prices and mill prices at the same time, and each consumer chooses one of them. In the equilibria, firms specialize in delivery services even if their transport costs are higher than consumers'. This result is...

In this study, I theoretically analyze fake reviews on a platform market using models where a seller creates fake reviews through incentivized transactions, and its sales depend on its rating based on a review history. The platform can control the incentive for fake reviews by changing the...

Assumptions on competitive structure are often crucial for marginal cost estimation and counterfactual predictions. This paper introduces tests for price competition among multi-product firms are introduced. The tests are based on the firm's revealed preference (revealed profit function). In...

We examined the effect of a rating system on sellers' entry into and exit from platform markets with monopolistic competition. We explicitly introduced a parameter for rating accuracy and analyzed sellers with varying product qualities by introducing a logit-type monopolistic competition. We...