The Power of Good Reviews

selling an ebookA few years ago, Yale professors Judith A. Chevalier and Dina Mayzlin did a study on the effect of user-generated Amazon reviews on sales . The authors made some fascinating observations:


  1. Good reviews significantly increase book sales
  2. 1-star reviews have a greater power to depress sales than 5-star reviews have to increase them
  3. Reviews are overwhelmingly positive at both Amazon and Barnes & Noble
  4. There are far more reviews on Amazon than Barnes & Noble, and they tend to be much longer


Just how much of an impact can good reviews make? While this is very hard to gage, the authors make a theoretical case:


Consider a book with no reviews at either site [Amazon and Barnes & Noble] whose price and other characteristics would suggest a sales rank of 500 at both sites. The posting of an additional 3 reviews at, if it didn’t alter the sales rank at, would be expected to lower the sales rank to number 327, implying incremental sales of approximately 57 books per week.


One of the more fascinating aspects of the study was the discovery of how powerful a 1-star review has to decimate sales. In fact, it has more power to lower sales than a 5-star does to increase them. This brought an eyebrow-raising observation from the authors:


One could argue that posting 1 star reviews of competing books could be a reasonable strategy for an author. We acknowledge that this may be true, although it is not at all clear that two books on the same subject, for example, are substitutes rather than complements.



For the record, I think it would be hideous for any author to do that.



The Difference Between Amazon and

The Yale study found some fascinating differences between the two sites:


  •’s total sales equal about 15% of’s North American sales.
  • has way more books with zero reviews than Amazon (54.22% versus 12.61%).
  • The median number of reviews is 11 on Amazon, and 0 on




How Many People Actually Post A Review?

Now that we have hard evidence of what most of us know intuitively (reviews affect sales), it becomes abundantly clear that you must do everything you can to get reviews posted to your books. The problem is that most people who love your book will not write one. Think of your own behavior. When was the last time you read a book, returned to Amazon, searched for it, clicked on the title and wrote a review?


To show you just how few people do it, consider this example. According to Amazon, the most reviewed book on the site is Harry Potter And The Order Of The Phoenix with almost 6,000 reviews. Amazing, no? Not really. Not when you realize Amazon sold millions and millions of copies!


My back of the envelope math shows that .0002% of readers of one of the best selling books ever left a review. In their Freakonomics blog, authors Steven Levitt and Stephen Dubner, estimate that 1 in 1,000 book purchasers post a review on Amazon. That’s .001%.


Sell Your Books Online


My point, and I do have one, is two-fold:


  1. Reviews are hard to come by.
  2. They make a HUGE difference in selling an ebook.


People who liked this article also enjoyed Selling An Ebook.


The good news is that you don’t have to have a lot of reviews for you to make money selling ebooks. I know some best sellers that have just a handful of reviews.   But the challenge is there and we must meet it: How do we get good reviews posted to our book page? We can do this by…


Using Permission-Based Strategies

Ever see an empty tip jar when you’re settling your bill at the cash register? Studies show that you’re far less likely to leave a tip in an empty jar than one that already has money in it. That’s the concept of “social proof” at work—using cues given by other people to guide our behavior. It’s the reason bars make people wait outside behind the velvet rope even though it’s nearly empty inside. It serves as social proof that it’s the place to party. Otherwise, why would there be so many people waiting in line?


For our purposes, the number of book reviews “waiting behind the velvet rope” defines social proof. To really grasp the impact that reviews have to exercise social proof, consider two competing books: They cost the same and cover the same subject matter. They both have clever titles, a well-designed cover and a compelling book description. But one has fifteen reviews and the other has none. Which is the better book? Social proof says most of us will pick the one with all the reviews.   In the absence of other evidence, they are “proof” the book is better.


Stay Tuned!  More posts about engaging book buyers coming soon.

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