This would typically take place in two ways; fake positive reviews to boost ratings and fake negative reviews to drag down competitors.
Nie and the team wanted to see if the competition introduced by Airbnb changed these behaviours. The study analysed 2,188 hotels in 67 Texas cities from 2008 (when Airbnb launched) to 2016.
Since high-end accommodation wouldn't compete with budget accommodation, the hotels and Airbnbs were separated into high and low-end and then compared.
United by a common enemy
After analysing the results, the report found that pressure from Airbnb listings increased the existence of fake positive reviews for high-end hotels. However, there was also a drop in fake negative reviews on hotels of a similar budget, which resulted in an increase of overall ratings.
Researchers said hotels chose "co-opetition instead of tit-for-tat."
In general, the emergence of Airbnb had little effect on whether low-end hotels posted fake positive or negative reviews. According to Nie, these hotels typically have fewer customer reviews and rely less on them.
"A lot of people who stay at low-end hotels are less likely to pay attention to reviews compared to people trying to decide if a $500 resort is worth their money," he said.
Those shelling out a lot of money would be more likely to scroll through reviews; something hotel managers are aware of.
Customers who are paying more or are choosing a hotel for the experience of staying there have higher expectations, he added. They're more likely to scroll through the reviews to look for any red flags before booking a room. Managers at high-end hotels recognize this.
"We have shown the evidence that if there are more Airbnb listings available around high-end hotels, those hotels tend to self-promote more by posting fake positive ratings. Consumers need to be careful because the reviews, especially on Tripadvisor, may be inflated and not be truly representative of the quality," said Nie.
Since Tripadvisor allows anyone to post a review (while Expedia only allows reviews from customers who have booked via the site or partner site), Nie said the difference in a hotel's rating between the two sites "offers an indication of the level of review manipulation."
Hotels could still skew ratings on Expedia by paying for rooms but the study's authors said it was less likely.
The small size of the report means it does not represent the entire industry, something Tripadvisor noted in response to Nie's paper.
"It was based on a small sample size in Texas which can hardly speak for the larger global hotel industry," said a spokesperson, who said the company uses a multi-layered approach to prevent fraudulent reviews.
“Tripadvisor takes the issue of fraud extremely seriously, and for the last 22 years, we’ve used the best in technology and human moderation practices to fight fake reviews,” they said.
