Airbnb originally released the data to counter criticism that it facilitated illegal commercial rentals. The company argues that most of its hosts are merely renting out extra space in their homes for some extra cash.

However, the researchers alleged in a report on Wednesday that Airbnb’s data gives a skewed picture of its New York listings. In fact, they said the company cherry picked data immediately after removing nearly 1,000 listings by hosts who rent multiple apartments.

“The intervention was so specific, and the timing so close to the date of the New York City snapshot, that the conclusion is inescapable: Airbnb removed listings from its site so that its data set would paint a more attractive picture of its business, to better influence media and public opinion,” the report said. “It was a cover-up, not a move to transparency.”

The researchers, Murray Cox and Tom Slee, built computer programs that collected and tracked data from Airbnb’s website about its listings over time, including an identifier for each host, the type of rental, and location. They looked at listings before Nov. 17, the date Airbnb used to showcase “typical” activity on its site, and listings after that.

They concluded that Airbnb manipulated the data based on several findings:

• There was a large and unusual drop off for listings of entire homes (rather than merely spare bedrooms) in New York City just days before Nov. 17. Cox and Slee estimated that more than 1,000 of these listings were removed as part of the purge, affecting more than 500 hosts, many of whom had multiple homes.
• The listings removed appeared to be concentrated among hosts with several listings, including three that had 10, 11, and 12 listings each in New York City. After the purge of listings, most of these hosts were left with only one home listed on Airbnb, which played to the company’s claim that 95% of hosts only list one unit.
• There was no similar drop off in “Private room” or “Shared room” listings, presumably because those types of listings are not central to the criticism of Airbnb as enabling landlords to turn long-term housing units into short-term hotels.
• Cox and Slee examined Airbnb listings in two other large markets, Miami and Los Angeles, and found no unusual drop off or change in listing activity, reinforcing their belief that the New York City drop off is an anomaly and not a result of a change in company-wide policy. They also found no change in listing activity in three European cities—Rome, London, and Berlin.
• Listings by landlords with multiple homes appear to be rising since Nov. 17, signaling that Airbnb isn’t making a long-term effort to keep them off the service.

The report also alleged that Airbnb made misleading projections along with the data about the share of income going to hosts with multiple listings compared to people with single listings. The company said that income for hosts with multiple properties will shrink from 41% to 14% of all revenue from entire home listings in New York City. Because Airbnb used the artificially low data from November 17, they argue, its projections are much lower than they should be.

An Airbnb spokesman disputed the report’s claims to Fortune:

The facts are clear for all to see – the vast majority of our hosts are everyday people who have just one listing and share their space a few nights a month to help make ends meet. Airbnb is an open people-to-people platform where listings come on and go off throughout the year. We’ve also done significant work to educate our community about what is in the best interest of their city and we routinely review our listings to ensure guests are having the quality, local experience they expect and deserve.

In November, Airbnb made a public pledge to be more transparent about activity on its site and to work with city officials and regulators. Shortly after, it released the New York City data, presumably because of the company’s tense history with city officials there.

Last year, the New York Attorney General’s office released a report that found that almost three-quarters of Airbnb listings in the city were illegal. After a lengthy legal battle, Airbnb agreed to send the attorney general’s office anonymized data about thousands of New York City listings.

Airbnb’s spokesman also shared a partial snapshot with Fortune of its New York City listings as of Feb. 8 that shows that 94% of hosts there only have one listing. Slee told Fortune he has similar data, but he pointed out that the number of New York City listings by hosts with more than one rental has been rising since the November purge.

For more about Airbnb, watch:

While Airbnb hosts with multiple listings may have shrunk to only 5% or 6% of the overall, they are not being prevented from re-listing their units.

Still, questions remain. Airbnb says it periodically removes listings that don’t meet the company’s standards, so it’s possible that this was the case just prior to Nov. 17. However, Cox and Slee find the timing odd because the sudden change only took place New York City and not any other market they researched.