|TRIVAGO N.V. filed this Form 20-F on 03/06/2018|
Return on advertising spend (ROAS)
We track the ratio of our Referral Revenue to our advertising expenses, or ROAS. We believe that ROAS is an indicator of the effectiveness of our advertising. Our ROAS was 113%, 120% and 115% for the years ended December 31, 2015, 2016 and 2017, respectively. Our ROAS in the Americas, Developed Europe and the Rest of World was 102%, 133% and 87% for the year ended December 31, 2015, respectively, as compared to 118%, 136% and 90% for the year ended December 31, 2016, respectively, and 116%, 131% and 92% for the year ended December 31, 2017, respectively. We believe the development of our ROAS among the reportable segments is primarily related to the different stages of development of our markets. For example, in Developed Europe, where we have operated the longest on average, we have historically experienced the highest average ROAS. Our ROAS in the Rest of World segment, where we have the lowest average ROAS, is also impacted significantly by the number of markets in the segment, including markets that we have recently entered and thus require significant advertising spend to reach scale. Over time, as our markets continue to develop, we believe that we will experience further increases in the efficiency of our advertising spend and thus improvements in our average ROAS. Given that advertising expenses account for the significant majority of our operating expenses, we believe this will have a direct impact on our operating margins and Adjusted EBITDA.
Historically, we believe that our advertising has been successful in generating additional revenue. We invest in many kinds of marketing channels, such as TV, out-of-home advertising, radio, search engine marketing, display and affiliate marketing, email marketing, social media, online video, mobile app marketing and content marketing.
Our ROAS by reportable segment for the years ended December 31, 2015, 2016 and 2017 was as follows: