Google's placement of its own flight-finding service in search results is resulting in lower click-through rates for companies that have not bought advertising, according to a study by Harvard University academics.
The study provides data for how Google's placement of its own services amid "organic" search results may hurt competitors, which is the focus of an ongoing antitrust case between Google and the European Union.
How paid and non-paid search results are displayed has a powerful sway over consumers, the study found. Ben Edelman, an associate professor at Harvard Business School, and Zhenyu Lai, a Harvard doctoral candidate, looked at when Google began inserting its own Flight Search feature, launched in December 2011, into search results.
They found that Google chose to display Flight Search depending on a user's search terms. When Flight Search was displayed, it takes a top position in the search results, pushing lower down non-paid search results.
The result was an 85 percent increase in click-through rates -- a key measure for advertisers -- for paid advertisements. Non-paid, algorithmically generated search results for competing travel agencies dropped 65 percent.
In an interview on Tuesday, Edelman said the study showed that Flight Search wasn't necessarily that popular with users. When Flight Search was displayed, however, users were more likely to click on AdWords, Google's advertising product.
"Users are surprised to see Google Flight Search," Edelman said. "They weren't expecting it. They don't necessarily like it or know they like it, but in the short run, it's not what they thought was going to be there, so they flee to AdWords.
For Google, it's all good, since the company collects revenue from AdWords.
The study analyzed data from ComScore's Search Planner, which is a database that tracks algorithmic and paid clicks on search engines by users who agreed to have their web surfing recorded.
Edelman and Lai compared Internet searches performed for four months prior to the launch of Google Flight Search and then after it launched from January to April 2012.
If a user searched for a flight in the format "flights to Orlando," Flight Search would be displayed. But if a user searched for "flight to Orlando FL," it was not displayed, they wrote.
It wasn't clear why slight query changes triggered the display of Flight Search. Edelman said it's even more difficult these days to predict whether Flight Search will be displayed.
But showing Flight Search caused as much as an 80 percent drop in algorithmic traffic to the five online travel agencies that had received the most traffic from the search terms used, the academics wrote. By contrast, click-through rates for paid advertising jumped 160 percent.
They warned that intermediaries such as Google have a powerful influence over consumers by ordering search results in differing formats. Edelman said it makes it more difficult for "vertical" search engines such as Yelp, which focuses on specific types of search such as restaurants, to compete.
"Google has a massive degree of control and uses that discretion in ways that services Google's interest but much less obviously serves other interests like the public or websites," he said.