You check out Facebook to see if one of your friends or someone in your family has done something interesting. Your attention is drawn to a holiday advert. That’s a coincidence, you think, because just before you went to Facebook you had been searching internet for a holiday destination. But this is no coincidence: dozens of parties are looking over your shoulder to see what you are getting up to on internet and this influences which adverts you get to see and where. PhD Candidate Robbert van Eijk investigated this process and the observance of privacy legislation in European countries. He will defend his doctoral thesis on 29 January.
The technology which facilitates online advertising is called ‘real-time bidding’ (RTB). When you visit a website, within a few tenths of a second the advert space on that page is ‘auctioned’: on the basis of data saved in cookies it is determined what kind of adverts are most relevant for you. The provider who places the highest bid for this kind of advert ‘wins’ and is given – upon payment of course – space by the advertiser to promote his product. ‘The motive to write this doctoral thesis came from the desire to investigate real-time bidding at the intersection between technology and the law’, Van Eijk explains. ‘I wanted to find out more about what happens when as a visitor to a website you get to see adverts which appear to be tracking your steps. This topic is relevant in light of the application of the General Data Protection Regulation (GDPR) and the current cookie legislation and its rules which are laid down, among others, in Article 11.7a of the (Dutch) Telecommunications Act.’
In his research Van Eijk demonstrates that this privacy component can be measured. ‘I combine law and data science in my research by applying mathematic algorithms to the network traffic picked up between the browser and the websites visited. Taking a network-science perspective to the privacy component of RTB is new, by being able to distinguish the networks of partners involved in an advertisement system when displaying an advert on the website which an internet user visits. These advertisement networks partly overlap one another. This new way of observing the process also shows which role partners have in an advertisement network in collecting and sharing the data of website visitors.’
Dominant companies
Van Eijk demonstrates in the research that two kinds of algorithms enable transparency in the mutual collaboration arrangements (the betweenness). ‘These are cluster edge betweenness and node betweenness. The first is a standard that is based on the shortest paths between the partners in an advertisement network. The algorithm solves an important issue: which RTB partners are clustered in an RTB system? The second solves another important issue: who are the dominant companies in a network of RTB partners? Node betweenness helps us to distinguish between the companies.’
In addition, the researcher provides transparency concerning various differences between European countries. ‘I show that a Graph-Based Methodological Approach (GBMA) can indicate the situation concerning differences in permission in 28 European countries; for example, differences in cookie notifications and cookie walls. In Europe we see two mechanisms in relation to permission. An implicit permission (where tracking cookies have already been installed before the end user has given permission) and a strict permission mechanism (where the legal requirements are implemented to the extent that no tracking cookies are (allowed to be) installed on the equipment of the end user or information can be read from the equipment when he visits a webpage). In this way, countries with implicit mechanisms can be compared to countries where strict mechanisms predominate. This leads to unequal rights.’
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