LONDON (AP) — A study by Oxford University researchers on how playing video games affects mental health used data from video game makers, marking what the authors say is a rare collaboration between academics and the game industry.

Lack of transparency from game makers has long been an issue for scientists hoping to better understand player behaviors.

The paper released Monday by the Oxford Internet Institute comes as video game sales this year have boomed as more people are stuck at home because of the pandemic and many countries have once again imposed limits on public life.

The findings are based on survey responses from people over 18 who played two games, Plants vs Zombies: Battle for Neighborville and Animal Crossing: New Horizons.

The study used data provided by the game makers, Electronic Arts and Nintendo of America, on how much time the respondents spent playing, unlike previous research that relied on imprecise estimates from the players. The video game industry has previously been reluctant to work with independent scientists, the paper noted.

Such partnerships might be needed for future research on the booming video game industry.

Academics “need broader and deeper collaborations with industry to study how games impact a wider, and more diverse, sample of players over time,” said Andrew Przybylski, the institute's director of research. “We’ll need more and better data to get to heart of the effects of games, for good or ill, on mental health.”

The research was funded by the Huo Family Foundation, a London-based foundation, and the Economic and Social Research Council, a U.K.-government funded public body.

The researchers said they found the actual amount of time spent playing was a small but significant positive factor in people’s well-being.

The paper said the level of enjoyment that players get from a game could be a more important factor for their well-being than mere playing time.

Some 2,756 players of Animal Crossing: New Horizons and 518 players of Plants vs Zombies: Battle for Neighborville responded to a survey, out of 250,000 invitations. They were asked to fill out a survey on their experiences that was matched up against playing time logged by the game companies.

While the paper has yet to be peer reviewed, academics who weren't involved in the research said it showed some strengths, such as accurately measuring game playing time.

“The fact that it’s the electronic data collected from the device is very good, it's very objective," said Paul Croarkin, a psychiatrist at the Mayo Clinic in Minnesota who has studied video gaming and children. He said he had “lingering questions" about the study and said the self-reporting nature of the survey was a weakness, but said the researchers presented their findings in a balanced way.

Joseph Hilgard, an assistant professor of social psychology at Illinois State University, also noted some limitations.

“This is correlational data, and so we cannot estimate the causal effect of video games on well-being," said Hilgard. He added that respondents may have been playing other games simultaneously for which playtime wasn't tracked. “Finally, the low response rates on the surveys may limit the generalizability of the results to the entire player base of these games."