[abelr]

I'd be curious to get examples of actual successful lawsuits resulting from A/B testing! Regarding the legality of it, in the US it is illegal to perform price discrimination when the intent is to directly harm your competition ([1], [2], [3]). However, first, Robinson-Patman does not apply to services [4], and secondly this is trying to avoid predatory pricing, and the supreme court ruled that price differentials are prohibited when the price differential "may be substantially to lessen competition". Similarly in the EU, Article 102 c) of the Treaty on the Functioning of the European Union prohibits price discrimination for companies in dominant position. It has however been significantly relaxed in United Brands v. Commission [5], where the court recognized that a dominant firm may charge different prices to reflect the competitive market.

In short, price A/B testing is legal and common practice for most companies, and VWO's article seems a bit too quick to jump to declaring it illegal.

[1] https://en.wikipedia.org/wiki/Sherman_Antitrust_Act_of_1890

[2] https://www.law.cornell.edu/wex/Clayton_Antitrust_Act

[3] https://en.wikipedia.org/wiki/Robinson%E2%80%93Patman_Act

[4] https://www.ftc.gov/tips-advice/competition-guidance/guide-a...

[5] https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A...

[Chris_Newton]

You might also like to look into the EU consumer protection rules, particularly the Consumer Rights Directive and its respective implementations in the member states and the UK. There is quite a lot of specific information that must be provided to customers during the buying process, and there are some serious penalties available if a merchant is found not to have done so.

In particular, if a customer might have seen multiple prices for the same thing around the time of purchase, for example on a pricing page checked on a phone and then on a checkout process completed on a PC, you would surely want to have solid evidence that the actual price charged had been clearly understood and accepted at the time of payment.

[abelr]

Absolutely! I remember reading this paper [0] about personalized pricing. The fact that personal data (an IP) is being used to inform prices has to be disclosed in the GDPR disclosure of a website. A very simple way to avoid a lot of those issues however is to have time-limited experiments in which 100% of Country's flow is directed towards one experiment (in the case of Corrily we keep track of which user saw what price when to insure the user will always see the same price).

[0] https://www.econstor.eu/bitstream/10419/205221/1/de-Streel-J...