|TRIVAGO N.V. filed this Form 20-F on 03/06/2018|
Referral metric is a helpful proxy for the number of unique visitors to our site with booking intent, which is the type of visitor our advertisers are interested in and which we believe supports bidding levels in our marketplace.
We had 334.6 million, 535.3 million and 727.1 million Qualified Referrals for the years ended December 31, 2015, 2016 and 2017, respectively, representing annual growth rates of 60.0% and 35.8% in 2016 and 2017, respectively.
We believe the primary factors that drive our Qualified Referral development are the number of visits to our websites and apps, the booking intent of our visitors, the number of available hotels on our hotel search platform, content (the quality and availability of general information, reviews and pictures about the hotels), hotel room prices (the price of accommodation as well as the number of price sources for each accommodation), hotel ratings, the user friendliness of our websites and apps and the degree of customization of our search results for each visitor. Ultimately, we aim to increase the number of Qualified Referrals we generate by focusing on making incremental improvements to each of these parameters. In addition to continuously seeking to expand our number of relationships with hotel advertisers, we partner with such hotels to improve content, and we constantly test and improve the features of our websites and apps to improve the user experience, including our interface, site usability and personalization for each visitor.
The following table sets forth the number of Qualified Referrals for our reportable segments for the periods indicated:
Note: Some figures may not add due to rounding.
Revenue per Qualified Referral (RPQR)
We use average Revenue per Qualified Referral, or RPQR, to measure how effectively we convert Qualified Referrals to revenue. RPQR is calculated as Referral Revenue divided by the total number of Qualified Referrals in a given period. Alternatively, RPQR can be separated into its price and volume components and calculated as follows:
RPQR = RPR x click-out rate
RPR = revenue per referral
click-out rate = referrals / Qualified Referrals
RPQR is determined by the CPC bids our advertisers submit on our marketplace as the CPC bids submitted by our advertisers play an important role in determining the prominence given to offers and their placement in our search results. Advertisers can analyze the number of referrals obtained from their advertisements on our marketplace and the consequent value generated from a referral based on the booking value they receive from users referred from our site to determine the amount they are willing to bid. Accordingly. the bidding behavior of our advertisers is influenced by the rate at which our qualified referrals result in bookings on our advertisers’ websites, or booking conversion, and the amount our advertisers obtain from Qualified Referrals as a result of hotels booked on their sites, or booking value, and the degree to which advertisers are willing to share with us the overall estimated booking revenues generated by our advertisers from our referrals, or revenue share, which we also refer to as "commercialization". We estimate booking conversion and booking value from data voluntarily provided to us by certain advertisers to better understand the drivers