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October 05, 2009

Why Yelp has a Review Filter

Here at Yelp, we're trying to connect people with great local businesses. Providing consumers with trusted review content is critical to this mission. One question we occasionally get asked on this topic is why reviews sometimes "disappear" from a business page. While the overwhelming majority of reviews aren't affected, we figured this might be a good time to offer some specifics on why reviews sometimes don't appear on business pages (and why we think this helps make Yelp the most useful consumer review site around).

Yelp has an automated Review Filter that many people are surprised to learn was put in place soon after our big launch in 2005. Of course, it's evolved over the years; it's an algorithm our engineers are constantly working on. Its purpose, however, remains the same: to protect consumers and business owners from fake, shill or malicious reviews.

Is this really an issue? It's said a picture is worth a thousand words, so....

Geek

That's a screen shot of an advertisement requesting fake reviews on Yelp. It's an attempt to manipulate the content that 25 million people relied on last month to find everything from a great restaurant to a trustworthy mechanic to a top-notch pediatrician.

This advertisement isn't a rarity. In fact, you'd be surprised how many of these we encounter. But, while most business owners focus on providing great service and let their business speak for itself, a very small percentage apparently would prefer to take a less than honest approach. That includes writing their own reviews, paying others to write reviews and, at times, even posting negative reviews on competitors' pages.

These types of practices aren't fair to consumers and they certainly aren't fair to other businesses. If they were allowed to occur, they would erode trust...which would reduce the usefulness of the site for both consumers and the good businesses that rely on the positive word-of-mouth they've earned. While Yelp relies heavily on our community members to catch shills and point out things that look suspicious, they can't be everywhere. (Though they're not shy if they find some.) That's why we believe our Review Filter makes Yelp stand apart from other review sites.

Is it a perfect system? No. Building a scalable, automated method to identify spurious reviews and protect the integrity of website content that includes more than 7 million reviews is difficult. Does legitimate review content sometimes get lost as a result? Yes. Our filter takes a conservative approach and errs on the side of protecting the consumer, when necessary. Customer reviews directly solicited by a business can fall into this category at times, which is why we caution against the practice. It's unfortunate, but this is what is required to maximize trustworthy content and provide value to consumers and businesses alike. And while we work to improve our system every day, we'd argue it's one of the more effective systems out there (if not the only).

The good news is Yelpers understand the challenge and appreciate the benefits. In a recent user survey we conducted, a whopping 94% of respondents said they turn to Yelp first to make a purchasing decision. Indeed, 80% noted it's because Yelp emphasizes reviews from trusted members of the community.

The goal of our community self-policing and automated review filtering is to make Yelp a trustworthy resource for connecting people with great local businesses. Some recent third-party data suggests we're heading in the right direction.

That said, we know our system's not perfect, and we always encourage feedback.

Update: Here's a video we made to help explain our review filter further.