It is a recognizable situation for many people who buy airline tickets online. If you look at prices for the same flight in the afternoon, the same seat is suddenly a lot more expensive than that morning. The alleged reason? The airline would know from cookies that you are interested in that seat and therefore increase the price.
Also in the media the rumor comes back every now and then. On Wednesday, July 10, the subject was raised at De Wild in the Afternoon on NPO Radio 2. "I want to book a plane ticket for early August," said sidekick Thijs Maalderink in the broadcast. "I had just looked this weekend: well, still reasonably affordable. I looked this morning: just 80 euros!"
"Yes, of course: cookies!" Was the reaction of another sidekick, Cielke Sijben. "They know what you are looking for and the price is adjusted - although I think that is no longer allowed, but I think it will happen that way. I think."
What is a tracking cookie?
- A tracking cookie ('tracking cookie') is a small file that is sent from the website to the internet browser of your computer or smartphone, intended to be able to follow a user over the internet.
- In addition to tracking cookies, there are other forms of cookies. They are not used specifically to follow you on the internet, but to keep a user logged in on the website, for example.
Can a price be adjusted based on cookies?
"Yes, the starting point is that you can sell things for whatever price you want," says Frederik Zuiderveen Borgesius, professor of ICT and private law at Radboud University and researcher at the University of Amsterdam. However, the price difference may not be based on discrimination. "For example, you cannot allow people with an immigrant background to pay extra, or let white people pay double."
"The person sitting next to you on the plane has probably paid a very different price than you." Christiaan Behrens, researcher
In addition, an airline, or web store, that wants to adjust its prices based on this information must make that clear to its visitors. To apply online price discrimination, the website must after all process personal data, such as tracking cookies, an e-mail address or the IP address.
The website must state this explicitly, for example in a privacy statement, says Zuiderveen Borgesius. "For example: 'we use your IP address and cookies that we have placed on your computer to adjust prices'. But I do not know of any examples of stores that admit that way. It is quite possible that this kind of personalized prices Not prevent the Netherlands. "
Do airlines adjust the price of airline tickets?
Yes, it is no secret that airline tickets fluctuate in price. "The person sitting on the plane next to you will most likely have paid a very different price than you", says Christiaan Behrens, researcher competition and innovation at SEO Economic Research and lecturer in transport economics at the VU University Amsterdam.
That every passenger goes up for a different price is probably because the tickets were bought at different times. To actually sell all seats on the aircraft, the price is frequently adjusted in the run-up to the departure time.
"For example, airlines know that people who book early are often not business travelers, because business travelers want more flexibility and will book later," the researcher says. As the departure date approaches, the prices of tickets become higher. "About ten days in advance you see a sharp increase in the price. That is also because the seats really run out. You are then competing with another traveler, who also wants to have the last seat."
Yet it is already difficult for an airline to determine whether someone is a business traveler or not, Behrens says. "If you fly to Madrid today, you can go there for vacation. If you fly to Barcelona next time, then that can also be a business trip. That distinction is difficult to make."
Is price discrimination also based on cookies?
"That is one of the questions that we currently have no scientific answers to," says Behrens. "There is no hard evidence that that actually happens."
Efthymios Constantinides, digital marketing researcher at the University of Twente, also agrees. As a lecturer, he oversaw several studies that showed that cookies do not play a role in the price differences of airline tickets. "There is a lot of anecdotal evidence, but I have not yet seen scientific evidence."
"If you delete your cookies and you see the price change, you don't know if that is because you have thrown your cookies away." Frederik Zuiderveen Borgesius, professor of IT and private law
In 2018, researchers from the KNU University in Kiev conducted research into price discrimination at four Ukrainian airlines. "They found no evidence that cookies and internet history affected the price of online tickets," says Constantinides. The researchers also found no evidence that the price was influenced by the fact that the consumer had previously looked at a competitor's website. Also, an earlier, unfinished attempt to buy tickets did not later lead to higher ticket prices.
Although no evidence has been found, relatively little research has been done into whether airlines profile consumers on the basis of cookies. This is also because research is difficult to carry out. "Flight tickets fluctuate in price almost like stock prices," says Zuiderveen Borgesius. "If you delete your cookies and you see the price change, you don't know if that is because you have thrown away your cookies, or because there is another reason you can't observe."
It is technically possible to offer visitors to a website a personalized price based on cookies and other information. Although the phenomenon is difficult to investigate, there is no evidence in various scientific studies that this is happening.
However, an airline can offer customers discounts or extras in other ways, for example through loyalty programs. However, this cannot be compared with online price discrimination based on user profiles. We therefore consider the statement that airlines adjust their prices using tracking cookies as unproven .
Response from Dutch airlines:
- Corendon and Transavia announce that prices are not adjusted based on cookies or a profile of the user.
- KLM did not respond to the questions that NU.nl has submitted to society.