Besides analyzing actual eBay transactions, the researchers conducted an experiment to see if people could tell the gender of sellers from user profiles. People guessed correctly in 1,127 of 2,000 cases, wrong in 170 and did not know the rest.

In another experiment, the researchers asked people to place value on a $100 Amazon gift card sold by someone named either Alison or Brad. On average, Alison’s gift card was valued at $83.34, while Brad’s was valued at $87.42.

Claudia Goldin, a Harvard economist and expert on gender wage gaps, said the study was intriguing but needed more analysis. “Just perceiving that somebody’s a woman, what exactly does it mean?” she asked. “It’s got to mean something about the quality of the good or service or something that’s not captured in the data that they have.”

Without that additional information, Dr. Goldin said her hunch is that “the majority of people would be bidding less if they thought that, ‘This really isn’t a 1948 Rolex’ or ‘This really isn’t Jackie Robinson’s signature.’ ”

The researchers said eBay allowed them access to data on transactions, sellers and buyers, including gender. They evaluated transactions from 2009 to 2012, focusing on the 420 most popular items in eBay’s broader categories, and on auctions because no negotiation is involved. Sellers considered to be stores were excluded.

EBay did not provide financing for the study, but set conditions, according to the authors and to editors at Science Advances. The researchers’ contract allowed eBay to approve any study before publication, mostly for potential disclosure of proprietary data and trade secrets; the authors said eBay “ended up approving the study without asking us to drop any of our results.”