“It’s an experiment for us, something we think could be very useful,” said Jassy, while speaking at the Wall Street Journal D Live conference on Tuesday. “So far, we’re really pleased with the early results.”

Amazon’s goal is to learn about how it can use data from its online e-commerce operation to boost sales at a retail store. Such data might include giving customers personalized book recommendations in real time, he posited. The stores could also help showcase Amazon’s growing hardware offerings, such as the Echo speaker and smart assistant.

Amazon, which is the largest online seller of books and many other items, started opening bookstores earlier this year. Then this month, reports emerged of of plans to open small Amazon grocery stores.

Amazon CEO Jeff Bezos said at the company’s annual shareholder meeting that the e-commerce giant is “definitely” opening more stores, although he did not reveal how many. “In these early days it’s all about learning, rather than trying to earn a lot of revenue,” Bezos said of the bookstores.

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Jassy said that Amazon (AMZN) is the rare company that experiments without worrying about failing. “We like to say that we’re working on many of our next big failures,” Jassy said.

Failures can still teach the company important lessons. Technology from Amazon’s poor selling Fire phone was incorporated into later successful products such as the Echo, he noted.