We all talk about Google and Facebook's rich data source for human behaviour. We talk less about Amazon's rich data source on consumer behaviour. As Google themselves once said Amazon is a search engine for products/shopping.[0] They said this some 3~ years ago, Amazon has continued to expand since. It is fairly safe to assume Amazon is the single most largest consolidated reserve of consumer behaviour data on the world now.

Facebook can gauge the difference between different types of likes from how you read a page[1], Amazon does too from their harvested clickstream.

[0] http://www.bbc.co.uk/news/technology-29609472

[1] http://www.slate.com/articles/technology/cover_story/2016/01...