User reviews have proven to be an effective sales driver, but there is more to it than just adding them to product pages. Once you start to get large amounts of reviews you need be able to sort them in a meaningful way for customers.

Usability expert Jared Spool has a great example of how Amazon managed to solve this problem for its customers and add $2.7bn to its bottom line.

In this article from The Economist last week, Google’s retail industry director John McAteer says that the amount of reviews is crucial for increasing conversions, with 20 the magic number, at which point the product becomes more attractive and inspires further reviews. 

However, once the number of reviews reaches a certain point, and users have too many to scroll through, then they need some help making more sense of them.

Amazon's solution is described by Jared Spool in his latest article, and was as simple as adding the question: 'was this review helpful to you?' which helped Amazon to place the most relevant reviews, and therefore the most useful ones for conversion, at the top.

Amazon quietly bumps the three most helpful reviews to the top. It tries to balance positive and negative reviews, so shoppers get a balanced perspective. An interesting side effect is how these selected reviews get more votes. If they are controversial (in that not everyone agrees they were helpful), their ratio goes down, allowing the most helpful reviews to bubble up past them. This makes it a self-managing system, letting the reviews people find the most helpful to maintain their standing at the top of the list. The result is an understated implementation that works great.

Other touches, such as allowing users to easily view the best negative or positive reviews, as well as some handy charts that summarise review ratings, make the large number of reviews manageable for users and more useful for Amazon.

Jared calculates that, since displaying the most helpful reviews has increased sales in the media products category by 20%, overall this feature was worth $2.7bn to Amazon, and after this example of a firm that made $300m by removing the need to register before checkout, shows how small tweaks can make a big difference.

This doesn't necessarily apply to all retailers, as few attract the sheer numbers of reviews that Amazon, In fact, it's hard to find too many UK e-commerce sites with a large number of reviews.

Kelkoo and Reevoo both ask if reviews were helpful, and this makes product pages easier for shopper to scan. Reevoo provides a useful summary of scores, and displays review in order of how helpful others found them: 

Reevoo reviews

On the Game website, there are a number of items with hundreds of reviews, but the retailer hasn't provided the tools to sort them and to help shoppers make more use of them. In this example for Grand Theft Auto, there are 217 user reviews split across 40+ pages:

Game reviews

Having gathered so much user feedback, Game is not making the most of it, and this is a clear case where the ability to rate reviews as helpful or otherwise could make them a valuable resource for shoppers, and help increase conversions for the retailer.

Graham Charlton

Published 19 March, 2009 by Graham Charlton

Graham Charlton is editor in chief at SaleCycle, and former editor at Econsultancy. Follow him on Twitter or connect via Linkedin.

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Comments (8)

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Really excellent article, will forward this to colleagues. Every site which features reviews or is about to implement must really consider sorting quite carefully.

over 9 years ago



Very interesting, I have always enjoyed the Amazon review ratings, and have always been impressed that the ones I see are helpful. I'm wondering what other areas this could be applied to..I'm sure the same logic would work in oother areeas.

over 9 years ago


Nick Stamoulis

It is def. important to keep the reviews clean and relevant. getting rid of what ever might not belong there to keep the integrity of that feature.

over 9 years ago


Justin Crandall

This is a very good article and I'd highly recommend clicking through to the Economist article referenced by Graham above. As noted in The Economist article, the volume of reviews drives a significant impact on conversion and return rates, so it's important retailers engage their customers to maximize volume.

For retailers who successfully generate a large quantity of reviews, helping consumers quickly find reviews relevant to them is important. Sorting by helpfulness is a great start, but retailers should also add sort by:

- Rating: customers often want to quickly see the best and worst reviews

- Review Length: longer, more contextual reviews are generally more helpful

- Top Reviewers: every site has leaders in the community whose opinions are highly valued by others

- Photo and Video Reviews: a picture speaks a 1000 words so make it easy to find those reviews

- Reviewer Attribute: if I'm an expert photographer, I want to quickly sort to see only the reviews from other experts

Bazaarvoice makes all of these and other options available by default. We believe enabling your customers to decide which reviews are relevant to them is a fantastic customer experience that translates to real value, as Amazon found. 

over 9 years ago



Good Article , reviews play a very important role conversion to sales . Reviews help a lot in changing the mentality of customer

over 9 years ago


Ian Brodie

A question on Justin's comment: Is there any evidence that video or photo reviews increase conversion?

A picture (or video) may speak 1000 words - but they also take rather longer to process than text. Personally I find them a huge waste of time - give me text anyday. But I recognise I may not be typical of Amazon or other retailer's target customers.


over 9 years ago



Amazon being deceptive? Nah... ;) It sounds like this small test proved substantial to their bottom line in sales in the billions.

over 8 years ago



I have to agree with the comment above (Ian Brodie), I find it very rare that I would site through a video review prior to making a purchasing decision. I would much rather scan the written reviews, primarily looking for anything bad, before making a decision on whether to buy or not.

about 7 years ago

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