Why Do People Post Reviews on Amazon?

I can understand why little-known authors and their friends post reviews of their own books at amazon. Judy Chevalier has a paper that finds that good online reviews sell a surprising number of books. (A bad review suppresses sales even more than a good review boosts sales, which also makes sense.)

More puzzling to me is why everyday people post reviews.

Take the latest Harry Potter book, for instance. It has been out about a week. So far there are 1,385 reviews at amazon, and another 385 at bn.com.

What’s in it for reviewer 1,385? It’s not at all obvious. Perhaps reviewers in general want to influence what gets read. But it is hard to believe that one review has much impact in a pile of 1,385 of them, or even among the 295 reviews of Freakonomics at Amazon.

No doubt developing a reputation for being a top reviewer is a motivation for some people. Amazon obviously likes to encourage these kind of reviewers by giving frequent reviewers titles like “Top 1000 reviewer.” But this can’t be the motivation for most reviewers either.

Maybe it just feels good to write a review?

On the flip side, of course, most people who read a book don’t post a review. For the typical book, I estimate about 1 in 1,000 book purchasers posts a review at Amazon. So maybe I’m looking at it wrong: anytime only in 1,000 people does anything, the question can just as logically be posed as why so few people write reviews.

Abbot Uhhm

I thought this nytimes article raised some interesting points about the media, the declining cost of entry to becoming a member of it, and the influence of the internet on the marketplace of ideas.
Perhaps one could view the inclination to post the umpteenth review of Harry Potter as arising from the same impulse as that which drove the cave painters.


I heard about your book from listening to NPR's Motley Fool and not from reading some review on Amazon. I think the author's interview was particularly compelling- enough to motivate a google search for websites that reference "Freakonomics". Incidentally, that's how I came across this blog. I intend to at least peruse your book the next time I'm at a bookstore. In other words, don't stress about a few cranks who write bad reviews for whatever reason.


Keep in mind that it takes a couple of days for reviews to be posted on amazon, and a review can't be left until the product is shipping. So many reviewers of Harry Potter 6 actually thought that they were maybe posting the first review.

Different River

The question is not so much why so many or so few people write reviews, but why, if the reviews are so influential don't all authors and publishers review their own books positively under assumed names, posing as unrelated readers?

I'm sure some authors do do that, but the fact that there are so many unreviewed books means that the overwhelming majority don't.

Dan Ryan

I'd venture that relatively obscure books have a higher review/reader ratio than more widely read books. Like several other commenters above, I confine my reviews to books where there are not many other reviews, and to books where I have some particular expertise that (in my view at least) makes my opinion more valuable.

Harry Potter is probably an extreme outlier, the volume of reviews being driven by the extremely large number of readers. Also that many Potter readers are children who are, as yet, unversed in diminishing marginal utility.


hey, as i was readin the blog, i was left wondering why people leave comments for every blog. these are opinions too. hell, there isnt a thing like "top 1000 commenter", is there? this led me to wonder why people have opinions at all. yeah, u've got a point buddy, ppl are to be stripped of their opinions so that they cannot distinguish quality from trash


On items other than books the reviews can be a godsend without ever mentioning what the review actually thinks of the content. When the English subtitles on an an opera DVD started to seem incoherent, off I went to Amazon to warn others -- and found that a previous reader had already posted the address to request a reworked version of the disk. Reviewers can also warn others of things like annoying cuts, a performer's off night, etc. that would never occur to the Amazon or Kirkus reviewer to mention. In this case the incentive may indeed be to help others, but also to flaunt one's specialized knowledge. ("This is the first performance of Prokofiev's 'War and Peace' I've EVER heard where they cut the Cossack chorus!")


Some people post reviews to have their say on the topic in general. Look up H. Bissinger's "Friday Night Lights" (the book, not the movie) and read all the complaints from people in that Texas town who feel that their depraved fixation on football was somehow misrepresented.


Why do (did) people post their comments here?


i think people post reviews for different reasons.

for instance, i only post reviews for books that i'm sooo enthusiastic about that i feel like everyone in the whole world should have the same wonderful experience i did. (this probably totals 5 books.) i also have posted a few reviews for books that i absolutely hated, especially if i'd seen that other people had praised them. in those cases, i wanted to warn off people who would be seduced by the good reviews so they wouldn't be disappointed like i was.

but then there are the people who are top reviewers, the ones who have written hundreds or thousands of reviews. those might be the people who wanted to be professional reviewers, but couldn't get jobs like that. or the people who just like to have their opinions aired on everything, etc. then it's more about them and their ego, rather than about the book or film or whatever.



Another good question might be: Why does Amazon post bad reviews? Why would a site in the business of selling products have a medium for former customers to tell prospective customers NOT to buy their product? Especially in light of Chevalier's findings that bad reviews have higher weight than good ones.

Why does Amazon have reviews at all?

Sonny M

I'm not to keen on many Amazon reviews.

Especially the political books.

Many of the so-called reviewers are simply partisians engaging in name calling warfare to promote their own views and agendas and slander the other side.

I've seen book reviews where it was clear the writer didn't read the book, but simply wanted to insult the author.

Its quite common on most political books to the point where "reviews" try to skew reader recommendations.


I think the 1 in 1000 figure you cite is quite low. That would put Amazon's sales figures for Freakonomics at close to 300,000. That would be Harry Potter level of sales. Last I heard, Freakonomics was around 400,000 units in total.

I would just say that people who write reviews were either really satisfied or really unsatisfied. They had something to say!


Consumerpedia.org is designed with most of this in mind, but as it is still very much a work in progress, any and all feedback from you or your readers on how to make it better would be greatly appreciated. Thanks!


I suspect it's for the same reason that people post their cat photos and random 3 a.m. hopped-up-on-coffee streams of consciousness to the internet. Unlike the latter, though, there are actually people who like cat photos and book reviews.


Hi from the Amazon reviewing world. Entertaining blog and ideas. Great to see
various perspectives. As for me:

I review
therefore I am

Reviewing at Amazon.com is my main hobby. I am a positive lifestyle reviewer with an interest in reviewing books, movies and music that promotes positive change in the world. I am convinced that the world can be changed through information and action, so I try to promote items that will help to bring about positive change. 

Reviewing is my lifestyle, I live to review! Reviews are my fascination with life on display. I just put most of
my thoughts about reviewing here:


Looking forward to reviewing your book too...



Some people have these top ten lists with reviews that they like to post around the place as well.

They would probably consider themselves to be building a folio of reviews.


The reviews probably contribute a lot to sales, especially on long tail books with fewer reviews. When I saw the "TOP 50 reviewer" badge on Amazon, it made me wonder.

This dude I saw, Robert Morris, is a "TOP 50 reviewer" with over 1500 reviews(!) And I clicked to list all his reviews. Five stars. Five stars. Five stars. Five stars. Same length, systematic approach, professional style. Well-written. And five stars again. Impatient as I am, I checked only the first few hundred of his reviews. All five-star reviews. All except for one 4-star and one 3-star. All other five. All. What does that imply, if anything? The guy only writes when he's read a fiver? OR... he doesn't like Gauss on pure principal and thinks everyone is beautiful in his/her own way... OR... he is in the business of selling five-star reviews for ... say 1000 bucks/piece. Not too tough a price for a professional review with the badge "TOP 50 reviewer" on the world's largest book store. And not too bad a way to make a couple of million bucks.

Btw. as of today he ranks #13 to be exact, so after a few dozen five-star reviews more the badge will say "TOP 10 Reviewer". Now that's gotta be worth more than a grand.



I have visited your site 293-times


So In reading this, I'm asking my self why I would post a comment in this. I think the answer lies along the same lines as the answer to the question why goto a concert.

Fandom. I want to hang out with people who like the same stuff as me so we can hang out and do talk about / do something related to that thing...

even if that thing is musing about data...