Microsoft last year launched the Bing-It-On campaign, a new effort supposed not only to promote its own Bing search engine, but also to show everyone that Google isn’t such an effective service as everyone seems to be believe these days.

In just a few words, Microsoft claims that more users choose Bing over Google and even though no statistics have been provided following its own studies, several clips published all over the web are supposed to play the role of the living proof in this case.

But Yale Law School professor Ian Ayres has managed to demonstrate that Microsoft’s uncanny findings aren’t exactly accurate by performing his own research on people ready to try both Bing and Google.

“We also interjected a bit of randomness into our study to test whether the type of search term impacts the likelihood that Bing is preferred. We randomly assigned participants to search for one of three kinds of keywords: Bing’s suggested search terms, popular search terms, and self-suggested search terms,” Ayres explained.

The results pretty much speak for themselves: 55 to 57 percent of the participants preferred Google, while only 35 to 39 percent picked Bing.

“Several of Microsoft’s claims are a little fishy. Or to put the conclusion more formally, we think that Google has a colorable deceptive advertising claim against Microsoft. It could be worth a lot of money on lost ad revenue if the claims misled people into thinking that a substantial majority of people prefer Bing over Google,” Ayres wrote on Freakonomics.

Microsoft hasn’t yet commented on this analysis, but don’t be too surprised if Redmond denies all accusations. In fact, the Bing-It-On campaign is part of a much larger anti-Google campaign called Scroogled and supposed to reveal some of the unfair practices the search giant has embraced to attract more users and sell ads.

Update (October 3, 2013): Microsoft has issued a statement to deny all accusations and explain that most users really pick Bing over Google in its Bing-It-On campaign.