'Top reviews' on Amazon help influence shoppers -- but posting more than 3 can backfire

‘Do we need a million reviews to make a good decision on what to buy? Probably not.’

UNIVERSITY PARK, Pa. — Online reviews are a five-star way to get potential buyers interested in a product, and so-called “top reviews” try to cut down on the information overload many shoppers feel while browsing for the best item. However, a new study finds that reading too many featured reviews alone can cause shoppers to lose interest in making a purchase.

Researchers from Penn State looked at more than two million customer reviews of 1,000 products available on Amazon during their study. Overall, “top” reviews that consumers endorsed were the most helpful and had the power to influence both higher sales and customer satisfaction.

The team also found, however, that even when the online retail giant used top reviews to cut down on the wealth of information available, posting too many featured reviews backfired and these posts lost their influence over shoppers.

“We found that there is a situation that when there are too many top reviews, you fall right back into the trap where there is just too much information for the consumer,” says Wael Jabr, an assistant professor of supply chain and information systems in the Penn State Smeal College of Business, in a university release. “In this natural experiment we had some products with just three top reviews and others with significantly more. For products with way more top reviews, we saw the value of those top reviews goes away.”

The data the Penn State team used included all review-related information, such as the overall number of reviews and featured reviews for each product. Study authors determined the overall sentiment consumers had for each product by looking at the star-ratings customers handed out. They also tracked Amazon’s sales rankings for each product over a 10-month period.

Star-ratings play a major role in customer behavior

Researchers based the effectiveness of top reviews on how the sales performance of these 1,000 items changed over the 10 months. Specifically, the team looked at how the ratings started to shift over time and how the product sales rank changed accordingly.

Jabr says e-commerce sites started incorporating “featured” reviews because their most popular items can end up attracting hundreds or even thousands of comments from buyers.

“For example, when Amazon put out the Echo Dot smart speaker, more than a million customers reviewed that product within the first four years of its release,” Jabr explains. “So, do we need a million reviews to make a good decision on what to buy? Probably not. At a certain point, then, companies started to realize there is an overload that customers will face when we have to navigate this content. Retailers eventually came up with a variety of ways to kind of help you navigate this content, one of which is featuring reviews.”

Whether the Amazon product had 10 reviews or 1,000 reviews, however, the team found that top reviews had more influence over shoppers if they matched the overall star-rating of that item. Simply put, consumers paid more attention to featured reviews that gave the same number of stars that the product had on average — for example, a four-star review on an item averaging four stars.

“When you look at the reviews, Amazon shows you the overall ratings of the reviews — for example, how many people gave it a four-star rating, or, how many people gave it a two or three, etcetera,” Jabr continues. “We wondered, then, if the top review effect can be amplified. And it can. We found that when the distribution of top reviews and the distribution of overall reviews match, then the power of top reviews to influence gains strength. It is almost like there is a confirmation when the top reviews match what the crowd is saying.”

So, how many reviews is too many?

Although the Penn State team says there may not be a “magic number” of reviews which get shoppers to buy certain products, there does seem to be a tangible limit on how much consumers want to read. That number appears to be three.

“While the natural experiment does not compare every combination of numbers — for example, two reviews compared to three reviews, or two compared to four — we found that products with three reviews faired better than products with a varying number of reviews ranging from four to 10,” Jabr reports.

Additionally, researchers say retailers may actually benefit from encouraging consumers to endorse other reviews instead of continually posting their own — adding to the information overload.

“Retailers often default to sending you an email saying, ‘Please rate our product,’ which we think is great,” Jabr concludes. “But when there are enough reviews, they may want to find a way to nudge the customers to decide on top reviews because that’s going to be much more valuable then writing one more review.”

The study is published in Management Information Systems Quarterly.

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