Focusing on search rankings, this study analyzes the possibility that online platform signaling mechanisms can be commercialized and used to distort market competition. It first explores Europe’s institutional changes with respect to the provision of search results and information by online platforms. The European Commission introduced new rules on P2B trading practices, and is also pushing for amendments to consumer laws. The regulations ensure that platform users are clearly informed about the main parameters determining ranking and whether the ranking has been directly/indirectly affected by any payments made by the business operator.

Furthermore, this study collected and empirically analyzed panel data on search rankings and hotel star ratings, significant matching mechanisms of the hotel reservation platform. It was found that the ratings given by the platform themselves are often much higher than those given officially, meaning that the star ratings may be used as a marketing tool rather than having informative value reliable signal of quality. Another statistical analysis of the relationship between search ranking, hotel rating and promotional tags reveals a weak possibility that hotels with higher platform rating than official rating are more likely to rank higher in search results. Given its influence on users, the transparency and fairness of platforms’ matching mechanism should be enhanced. That is, online platforms are responsible for providing users with clear to distinguish between objective information and advertisement or paid information in determining ratings and information tags as well as search rankings.

Preface
Executive Summary

Chapter 1 Introduction

Chapter 2 Policy Trends Related to Search Rankings
　Section 1 Institutional Changes in Europe
　Section 2 Enforcement Cases in the United Kingdom

Chapter 3 Empirical Analysis of Search Rankings in Hotel Reservation Platforms
　Section 1 Overview of the Empirical Analysis
　Section 2 Empirical Analysis of Platform Matching Mechanisms and Search Rankings
　Section 3 Information Disclosure on Platform Search Rankings and Ratings

Chapter 4 Conclusion

References
Appendix
ABSTRACT